Sexual Dysfunction Among Adolescent and Young Adult Men Diagnosed with Cancer

Abstract

Purpose:

Adolescent and young adult (AYA) cancer patients frequently demonstrate sexual dysfunction; however, there is a lack of data quantifying the severity and frequency.

Methods:

Males aged 18–39 years, diagnosed with cancer of any kind and who were scheduled to begin, were actively receiving, or had completed cancer treatment within 6 months, were offered validated surveys during their oncology appointment. These surveys included the International Index of Erectile Function (IIEF-6), Masturbation Erection Index (MEI), 36-Item Short Form Survey, and 5-point Likert scales to assess their desire and ability to engage in sex and masturbation.

Results:

Forty subjects completed the IIEF survey with a mean score of 17.7 ± 11, erectile dysfunction (ED) prevalence accordingly was 58%. Thirty-eight subjects completed the MEI with a mean score of 25.3 ± 5.3, ED prevalence was again 58%. Age and IIEF scores demonstrated a statistically significant (p < 0.05, n = 38) Pearson's correlation coefficient of 0.40, patients younger than 30 years had an ED prevalence of 72% (mean IIEF 13), whereas patients aged 30 years and older had an ED prevalence of 45% (mean IIEF 22). All treatment modalities had ED rates >30%: chemotherapy demonstrated the highest prevalence at 64% (mean IIEF 17), whereas radiation therapy had the lowest prevalence at 33% (mean IIEF 23).

Conclusion:

This study demonstrates that the prevalence of sexual dysfunction among male AYA patients undergoing treatment for cancer is high. AYA oncologists should discuss potential sexual health concerns when treating this population. The exact cause of ED (non-organic vs. organic) within this group should be explored further.

Introduction

Approximately 70,000 adolescent and young adults (AYA), defined as 15–39 years of age, are diagnosed with cancer annually in the United States.¹ Pediatric cancer survivors, especially those exposed to radiation and chemotherapy, have higher rates of gonadal dysfunction and infertility.² These same treatment modalities are well documented to cause erectile dysfunction (ED) in older patients.^3,4

Despite these statistics, studies demonstrate that most oncologists do not discuss sexual function with their patients.^5–7 One study found that only 58% and 7% of young adults received discussions about reproductive and sexual health, respectively, at their initial oncology consultation.⁸ In another study, which interviewed 22 childhood cancer survivors, every participant reported that they were unsatisfied with their clinical support for their sexual health and the topic of sexual function was rarely brought up by oncologists despite the patient's desire for there to be such a discussion.⁹

The lack of sexual health discussions continues to the adult level; a survey of 66 patients attending a cancer survivorship clinic found that 97% of patients reported infrequent communication with their oncologist about sexual dysfunction and 94% reported that their oncologist was unlikely to initiate discussion about sexually functioning.⁷

ED is on the rise in men between the ages of 18 and 40 years, reaching as high as 30.8% in this population.¹⁰ Previous reports on the prevalence of ED among male pediatric cancer survivors have demonstrated varying results; some have shown higher rates of ED, whereas other have shown no difference when compared with age-matched controls.^11,12 However, recent studies have shown female pediatric cancer survivors have higher odds of reporting sexual dysfunction after treatment.¹³

Studies suggest that AYA cancer patients, overall, have worse symptom burden and associated mental health concerns compared with older adults.¹⁴ With an overall increased risk of poorer mental health and negatively impacted quality of life, male AYA subjects diagnosed with cancer who are currently undergoing or recently completed chemotherapy and/or radiation therapy are likely at higher risk for ED. Data regarding erectile issues in this group of patients are scarce—only one study was found to directly evaluate ED in males who were childhood cancer survivors, concluding that those males who survived childhood cancer had a >2.6 times increased risk for ED than the average population.¹²

To date, there is no literature that evaluates sexual health and ED in AYA males currently diagnosed with cancer. This study aimed to evaluate the sexual health and erectile function of male AYA subjects diagnosed with cancer who are either actively undergoing or have recently completed treatment. We hypothesized that there would be a high prevalence of ED among AYA males diagnosed with cancer.

Materials and Methods

This cross-sectional study was conducted at the University of Miami Miller School of Medicine and the University of Iowa Hospitals and Clinics and approved by the institutional review boards at both institutions. Subjects were enrolled from May 28, 2019, to February 22, 2021. Informed consent was obtained by survey respondents. Eligible subjects were males, 18–39 years of age, diagnosed with cancer of any kind and who were scheduled to begin, were actively receiving, or had recently completed cancer treatment within the preceding 6 months.

Subjects agreeing to participate completed validated surveys, including the International Index of Erectile Function (IIEF-6), Masturbation Erection Index (MEI), and 36-Item Short Form Survey (SF-36). An IIEF-6 score ≥26 indicated no ED, 18–25 minimal ED, 11–17 moderate ED, and ≤10 severe ED.^15,16 An MEI score ≤27 indicated ED on self-induced masturbation.¹⁷ Additionally, later in the study, new subjects were offered 5-point Likert scales evaluating sexual and masturbatory desires. These surveys were created by the research team to assess changes in a subject's libido, due to concerns raised by patients.

These surveys were provided physically in clinic or electronically. Subjects in Iowa were consented electronically, and once consent was obtained, they were directed to electronic surveys. In Miami, consent was obtained and physical surveys were distributed by oncologists agreeing to participate in the study and members of the urology research team during eligible subjects' oncology appointments.

Type of cancer and treatments, including chemotherapy, radiation, surgery, and duration of treatment, were recorded per a chart review. Sexual activity in the past 4 weeks was queried as a component of the IIEF survey.

All statistical analyses were performed in Excel (version 2108, Build 14326.20404; Microsoft) and Stata (version 17.0; StataCorp, College Station, TX). Student t-tests were utilized for determination of significance between the groups, set at a p value <0.05.

Results

Forty male subjects participated in the study. Participation in the surveys varied due to some subjects not completing all surveys, given their sensitive nature. In addition, a decision was made during the study to add survey questions to evaluate sexual and masturbatory desires. The mean age was 29 ± 5.0 years (range 19–38 years). The mean time elapsed since initial therapy was 242 ± 279 days (range 6–1132 days). Most commonly reported cancers were lymphoma (24%), testis (24%), leukemia (24%), and brain/central nervous system (12%). Of 38 respondents, 33 (87%) received chemotherapy, 6 (16%) radiotherapy, 12 (32%) surgery, and 2 (5%) transplant. Sixteen (42%) subjects received more than one of these treatment modalities (Table 1). All subjects completed the IIEF survey with a mean score of 17.7 ± 11.

Table 1.

Survey Subjects' Demographic Information and Corresponding Prevalence of Erectile Dysfunction by International Index of Erectile Function-6 and Masturbation Erection Index Scores

Characteristic	n (%)	ED prevalence by IIEF-6, n (%)	Mean IIEF-6 score	ED prevalence by MEI, n (%)	Mean MEI score
Gender identity (n = 40)
Male	40 (100)	23 (58)	17.7 ± 11	22 (58)^a	25.3 ± 5.3
Female	0 (0)	—	—	—	—
Age in years (n = 38)
18–25	9 (24)	5 (56)	15 ± 13	6 (67)	26 ± 3.8
26–29	9 (24)	8 (89)	12 ± 10	7 (78)	24 ± 3.7
30–35	15 (39)	9 (60)	19 ± 11	8 (62)^a	24 ± 7.5
36–39	5 (13)	0 (0)	30 ± 0.55	1 (20)	29 ± 2.7
Sexual activity in past 4 weeks (n = 40)
Yes	29 (73)	13 (45)	22 ± 9.3	14 (52)^a	26 ± 6.0
No	11 (27)	10 (91)	5.7 ± 7.5	8 (73)	26 ± 4.0
Cancer diagnosis (n = 38)
Testicular	9 (24)	4 (44)	16 ± 13	3 (33)	28 ± 2.4
Lymphoma	9 (24)	6 (67)	18 ± 11	9 (100)	21 ± 6.8
Brain/CNS	5 (12)	1 (20)	25 ± 12	1 (20)	29 ± 1.4
Leukemia	9 (24)	7 (78)	17 ± 9.8	5 (71)^a	23 ± 5.7
Sarcoma	2 (5)	2 (100)	4	2 (100)	25
Other	4 (11)	1 (25)	22 ± 15	2 (50)	28 ± 2.6
Therapy treatment (n = 38, multiple responses possible)
Chemotherapy	33 (87)	21 (64)	17 ± 11	21 (68)^a	25 ± 5.7
Radiation therapy	6 (16)	2 (33)	23 ± 11	4 (67)	27 ± 2.2
Surgery	12 (32)	6 (50)	18 ± 13	4 (33)	28 ± 2
Transplant	2 (5)	1 (50)	16 ± 16	2 (100)	12 ± 9.2
Time elapsed since initial therapy in days (n = 28)
1–182	15 (54)	6 (40)	20 ± 12	8 (53)	27 ± 4.0
183–365	7 (25)	5 (71)	18 ± 11	4 (67)^a	25 ± 3.6
366–547	3 (11)	3 (100)	4.33 ± 0.58	2 (67)	24 ± 6.0
548–730	1 (4)	0 (0)	30	0 (0)	30
731–912	0	—	—	—	—
913–1095	1 (4)	1 (100)	19	1 (100)	19
1096–1277	1 (4)	0 (0)	27	1 (100)	27

Adjusted for subjects without a completed MEI survey.

CNS, central nervous system; ED, erectile dysfunction; IIEF-6, International Index of Erectile Function-6; MEI, Masturbation Erection Index.

Thirty-eight subjects completed the MEI with a mean score of 25.3 ± 5.3. Prevalence of ED was 58% according to MEI and IIEF-6. Age and IIEF scores demonstrated a statistically significant (p < 0.05, n = 38) positive Pearson's correlation coefficient of 0.40. This was manifested by a significant increase in ED rates (p < 0.05) in patients younger than 30 years (72%, mean IIEF 13) compared with patients aged 30 years and older (45%, mean IIEF 22). Patients diagnosed with lymphoma, testicular cancer, leukemia, and sarcoma all had an ED prevalence >30% according to IIEF and MEI. All treatment modalities had ED rates >30%: chemotherapy demonstrated the highest prevalence at 64% with a mean IIEF of 17, whereas radiation therapy had the lowest prevalence at 33% with a mean IIEF of 23.

The odds ratio of a patient with ED (IIEF-6 < 26) to select that their sexual desire was “sometimes” or “less than half the time” rather than “most times” was 1.19 (p = 0.036) compared with subjects without ED (IIEF-6 ≥ 26). This indicates a negative association between ED and sexual desire. Results for sexual and masturbatory desires are shown in Tables 2 and 3, respectively.

Table 2.

Results of Survey Evaluating Sexual Desire (n = 18)

How often have you felt sexual desire?
Almost never or never = 0%	A few times (less than half the time) = 22%	Sometimes (about half the time) = 17%		Most times (more than half the time) = 61%	Almost always or always = 0%
How would you rate your level of sexual desire?
Very low or none at all = 11%	Low = 22%	Moderate = 11%		High = 56%	Very high = 0%
How satisfied have you been with your overall sex life?
Very dissatisfied = 11%	Moderately dissatisfied = 22%	Equally satisfied and dissatisfied = 28%		Moderately satisfied = 22%	Very satisfied = 17%
How satisfied have you been with your sexual relationship with your partner?
Very dissatisfied = 0%	Moderately dissatisfied = 0%	Equally satisfied and dissatisfied = 22%		Moderately satisfied = 0%	Very satisfied = 39%	Not applicable = 39%
Has your desire to engage in sex changed since you were diagnosed with cancer?
Very much decreased = 22%	Somewhat decreased = 22%	No change = 44%		Somewhat increased = 11%	Very much increased = 0%	Not applicable = 0%
Has your ability to engage in intercourse changed since you were diagnosed with cancer?
Very much decreased = 33%	Somewhat decreased = 33%	No change = 22%		Somewhat increased = 0%	Very much increased = 0%	Not applicable = 11%
Over the past 4 weeks, were you able to insert your penis into your partner?
Yes = 39%				No = 61%
Over the past 4 weeks, did your erection last long enough for you to have successful intercourse?
Yes = 67%				No = 33%
How would you rate the hardness of your erection?
Penis does not enlarge = 0%	Penis is large but not hard = 0%		Penis is hard but not hard enough for penetration = 0%		Penis is hard enough for penetration but not completely hard = 67%	Penis is completely hard and fully rigid = 33%

Table 3.

Results of Survey Evaluating Masturbatory Desire (n = 16)

How often have you felt desire to masturbate?
Almost never or never = 0%	A few times (less than half the time) = 25%	Sometimes (about half the time) = 75%	Most times (more than half the time) = 0%	Almost always or always = 0%
How satisfied have you been with your desire to masturbate?
Very dissatisfied = 0%	Moderately dissatisfied = 13%	Equally satisfied and dissatisfied = 38%	Moderately satisfied = 25%	Very satisfied = 25%
How satisfied have you been with your ability to masturbate?
Very dissatisfied = 0%	Moderately dissatisfied = 6%	Equally satisfied and dissatisfied = 25%	Moderately satisfied = 31%	Very satisfied = 38%
Has your desire to masturbate changed since you were diagnosed with cancer?
Very much decreased = 13%	Somewhat decreased = 38%	No change = 38%	Somewhat increased = 13%	Very much increased = 0%
Has your ability to masturbate changed since you were diagnosed with cancer?
Very much decreased = 0%	Somewhat decreased = 44%	No change = 56%	Somewhat increased = 0%	Very much increased = 0%

As for satisfaction (n = 18), when asked “How satisfied have you been with your overall sex life?” three (17%) subjects were “very satisfied,” all of whom had an IIEF score >26, and four (22%) answered “moderately satisfied,” two of whom had an IIEF score >26. All subjects who answered “equally satisfied and dissatisfied” (five, 28%) or either of the dissatisfied options, “moderately dissatisfied” (four, 22%) or “very dissatisfied” (two, 11%), had IIEF-6 scores <26. This demonstrates that the majority of AYA oncology patients are either neutral or dissatisfied about their overall sex life, and those who are moderately or more satisfied typically do not have ED.

The mean SF-36 response values (n = 22) are presented in Table 4. When grouped by IIEF-scores, those reporting ≥26 demonstrated consistently higher SF-36 scores in both the physical and mental domains when compared with the IIEF <26 group. A statistically significant (p < 0.05) positive Pearson's correlation coefficient was noted between IIEF-6 scores and emotional well-being (r = 0.53). A statistically significant (p < 0.05) correlation was also noted between MEI scores and social functioning (r = 0.49). Additional differences when categorized by ED severity can be seen in Figure 1. These results indicate that the severity of ED has a negative correlation with quality of life.

FIG. 1.

SF-36 domain mean values according to ED severity. No ED = IIEF-6 score ≥26 (n = 12), minimal ED = 18–25 (n = 2), moderate ED = 11–17 (n = 1), and severe ED = ≤ 10 (n = 7). ED, erectile dysfunction; IIEF-6, International Index of Erectile Function-6; SF-36, 36-Item Short Form Survey.

Table 4.

36-Item Short Form Survey Response Values for Each Respective Category

	Physical function	Role limitations due to physical health	Role limitations due to emotional problems	Energy/fatigue	Emotional well-being	Social functioning	Pain	General health	Health change
All responses (n = 22)	85.45 ± 23.88	52.27 ± 46.41	65.08 ± 41.76	57.05 ± 20.87	72.18 ± 18.11	72.16 ± 28.19	85.45 ± 21.85	70.45 ± 15.88	55.68 ± 28.14
IIEF ≥26 (n = 12)	97.08 ± 5.57^*	70.83 ± 37.96^*	80.56 ± 31.79	64.17 ± 18.24	81.67 ± 15.70^*	83.33 ± 15.59^*	91.04 ± 15.46	77.50 ± 10.31^*	56.25 ± 23.11
IIEF <26 (n = 10)	71.50 ± 29.33^*	30.00 ± 45.83^*	44.44 ± 44.45	48.50 ± 20.62	60.80 ± 13.72^*	58.75 ± 33.56^*	78.75 ± 26.11	62.00 ± 17.20^*	55.00 ± 33.17
Pearson's correlation coefficient between domain and IIEF score (n = 22)	0.35	0.24	0.23	0.21	0.53^*	0.20	0.0092	0.30	−0.23
Pearson's correlation coefficient between domain and MEI score (n = 22)	0.38	0.21	0.21	0.31	0.13	0.49^*	0.27	0.24	−0.095

Each score represents a percentage (out of 100). A lower score indicates increased disability in the respective category. The bottom two rows consist of Pearson's correlation coefficients between each SF-36 domain and IIEF-6 or MEI scores.

Statistically significant difference (p < 0.05) between IIEF ≥26 group and IIEF <26 group or statistically significant (p < 0.05) Pearson's correlation coefficient.

IIEF, International Index of Erectile Function; MEI, Masturbation Erection Index.

Discussion

This project sought to uncover whether AYA males undergoing cancer treatment experience self-reported sexual dysfunction. The extent to which this population experiences sexual dysfunction has been inadequately studied. Cancer patients often report dissatisfaction surrounding discussions of sexual function with their oncologists. Most pediatric oncology clinicians identify that they play a role in the discussion in the sexual health of their patients but feel that they lack proper education and support.¹⁸ Thus, there is a need to identify the true prevalence of ED among AYA males undergoing cancer treatment so that underlying causes or other treatment modalities may be pursued accordingly.

We performed a cross-sectional study of AYA males undergoing cancer treatment to assess the prevalence of sexual dysfunction, utilizing IIEF-6, MEI, and 5-point Likert scales to assess their desire and ability to engage in sex and masturbation since their diagnosis. Our data indicate that AYA males undergoing cancer treatment experience self-reported sexual dysfunction. Fifty-eight percent of subjects had at least some degree of ED according to IIEF-6 and MEI scores, which is greater than that demonstrated in the general population. This is consistent with previous studies reporting ED from radiation and chemotherapy in older patients and pediatric patients.^12,19–21

Previous studies on the prevalence of ED in young male populations demonstrate that ∼30% of young men in the general population experience ED, exhibiting a direct correlation with poor mental health (i.e., depression), unprescribed medication use, length of sexual life, and physical health.^22,23 This increased prevalence of sexual dysfunction has been reported in previous studies, where more than half of AYA cancer patients reported sexual dysfunction even 2 years after their diagnosis.²⁴ To the best of our knowledge, this is the first study to assess sexual function in AYA males diagnosed with cancer who are either actively undergoing or have recently completed treatment. Furthermore, it is the only study to utilize MEI in this population.

Overall health assessed via the SF-36 demonstrated a positive correlation with IIEF-6 scores. This means patients with more severe ED reported worse quality of life. Whether ED is a result of poor quality of life, rather than quality of life decreasing as a result of ED is unclear; however, a negative association between the presence of ED and quality of life has previously been reported in adults.²⁵ Traditionally, ED in young men was thought to be almost exclusively psychogenic (depression, anxiety) in nature, but physiological causes, such as neurological damage, endocrine disorders, vasculogenic, and structural abnormalities, have recently gained recognition.²³

Studies have demonstrated a large range, between 13% and 83%, of ED cases in young men being primarily psychogenic; such a wide range in reported prevalence is likely due to the multifactorial pathophysiology with which ED may present.^26,27 Cancer is reported to have a direct correlation with a high degree of depression in patients, which demonstrates a significant association with ED.^28–30 Previous studies have demonstrated physiological causes of ED in patients treated with chemotherapy and chemoradiation, including hypogonadism and cavernosal arterial insufficiency.³¹ In adult patients with prostate cancer, radiation therapy causes significant arterial damage with alterations to internal pudendal artery tone and a reduction of motor function in the cavernous nerve.²¹

Subjects in our study demonstrated >30% ED prevalence among all treatment groups: chemotherapy (n = 33) demonstrated a prevalence of 64% and 68% according to IIEF-6 and MEI scores, respectively, whereas radiation (n = 6) varied from 33% by IIEF-6 to 67% by MEI. The higher prevalence of ED among the chemotherapy group may be due to its systemic effects, whereas treatment with radiation and surgery can be localized. It is possible that physiological causes (hypogonadism and cavernosal artery insufficiency) and psychogenic causes (depression) may all contribute to ED in some male AYA cancer patients.

The majority of subjects reported either no change or a decrease in their desire to engage in sex and masturbation after their diagnosis of cancer. The exact cause of some patients' decreased desire to engage in sexual activity should be explored in future studies. It is currently unclear whether the cause is due to sexual dysfunction or related to social and/or psychological factors. As noted in past studies, sexual desire influences the correlation between sexual function and sexual bother (meaning men with greater sexual desire are bothered to a greater degree by decreased erectile function).³² Research has also demonstrated that sexual desire appears to be positively correlated with masturbation frequency.³³ The possibility of decreased ability to masturbate affecting overall sexual desire should be examined in future studies.

Common treatment methods for ED, such as phosphodiesterase-5 inhibitors, which are utilized in older patients, have been proven to be effective in younger male patients as well.^34,35 It is possible that properly addressing sexual health in AYA cancer patients may improve their quality of life and thus treatment outcomes. At the very least, oncologists should be aware of the potential negative impact sexual dysfunction can have on AYA patients and offer a discussion on the matter. This would allow oncologists to identify and appropriately refer patients with sexual dysfunction to sexual health experts.

Limitations

Our study captured sexual function of patients who had recently began, were actively receiving, or had recently completed cancer treatment within 6 months and, therefore, we are unable to make long-term conclusions about the sexual health of these patients. Future studies should aim to evaluate the long-term sexual and fertility-related effects of a cancer diagnosis on young adults. Furthermore, many subjects in this study did not complete all surveys, thus each survey's response rate varied.

Conclusions

AYA cancer patients currently undergoing or having completed treatment within 6 months demonstrate an increased prevalence of sexual dysfunction, compared with non-oncologic AYA patients, when evaluated by either IIEF-6 or MEI. Furthermore, younger patients demonstrate a higher prevalence and more severe ED according to IIEF and MEI scores. This raises the importance of oncologists to address ED in this population.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

Funding Information

No funding was received for this project.

References

, Dreyzin

, Miller

, et al. Adolescent and young adult oncology-past, present, and future. CA Cancer J Clin. 2019; 69(6):485–96.

Yoon

, Park

, Ju

, et al. Gonadal and sexual dysfunction in childhood cancer survivors. Cancer Res Treat. 2017; 49(4):1057–64.

Voznesensky

, Annam

, Kreder

. Understanding and managing erectile dysfunction in patients treated for cancer. J Oncol Pract. 2016; 12(4):297–304.

Peltier

, van Velthoven

, Roumeguere

. Current management of erectile dysfunction after cancer treatment. Curr Opin Oncol. 2009; 21(4):303–9.

Krouwel

, Albers

, Nicolai

MPJ

, et al. Discussing sexual health in the medical oncologist's practice: Exploring current practice and challenges. J Cancer Educ. 2020; 35(6):1072–88.

Bräutigam

, Schratter-Sehn

, Kottmel

, et al. Do radiation oncologists talk about sexual health and dysfunction with their cancer patients? Results of the igls-vienna-sexmed-survey. Clin Transl Radiat Oncol. 2020; 21:120–6.

Sporn

, Smith

, Pirl

, et al. Sexual health communication between cancer survivors and providers: how frequently does it occur and which providers are preferred?. Psychooncology. 2015; 24(9):1167–73.

Wang

, Chen

, Ruan

, et al. Discussions about reproductive and sexual health among young adult survivors of cancer. Cancer Med. 2016; 5(6):1037–46.

Frederick

, Recklitis

, Blackmon

, et al. Sexual dysfunction in young adult survivors of childhood cancer. Pediatr Blood Cancer. 2016; 63(9):1622–8.

10.

Landripet

, Stulhofer

. Is pornography use associated with sexual difficulties and dysfunctions among younger heterosexual men?. J Sex Med. 2015; 12(5):1136–9.

11.

Zebrack

, Foley

, Wittmann

, et al. Sexual functioning in young adult survivors of childhood cancer. Psychooncology. 2010; 19(8):814–22.

12.

Ritenour

, Seidel

, Leisenring

, et al. Erectile dysfunction in male survivors of childhood cancer—a report from the childhood cancer survivor study. J Sex Med. 2016; 13(6):945–54.

13.

Greenberg

, Khandwala

, Bhambhvani

, et al. Male and female sexual dysfunction in pediatric cancer survivors. J Sex Med. 2020; 17(9):1715–22.

14.

Mao

, Armstrong

, Bowman

, et al. Symptom burden among cancer survivors: impact of age and comorbidity. J Am Board Fam Med. 2007; 20(5):434–43.

15.

Rosen

, Cappelleri

, Smith

, et al. Development and evaluation of an abridged, 5-item version of the International Index of Erectile Function (IIEF-5) as a diagnostic tool for erectile dysfunction. Int J Impot Res. 1999; 11(6):319–26.

16.

Ramanathan

, Mulhall

, Rao

, et al. Predictive correlation between the International Index of Erectile Function (IIEF) and Sexual Health Inventory for Men (SHIM): implications for calculating a derived SHIM for clinical use. J Sex Med. 2007; 4(5):1336–44.

17.

Limoncin

, Gravina

, Lotti

, et al. The Masturbation Erection Index (MEI): validation of a new psychometric tool, derived from the six-item version of the International Index of Erectile Function (IIEF-6) and from the Erection Hardness Score (EHS), for measuring erectile function during masturbation. BJU Int. 2019; 123(3):530–7.

18.

Frederick

, Campbell

, Kenney

, et al. Barriers and facilitators to sexual and reproductive health communication between pediatric oncology clinicians and adolescent and young adult patients: the clinician perspective. Pediatr Blood Cancer. 2018; 65(8):e27087.

19.

Allameh

, Azghandi

, and Fallah Karkan

. Is chemotherapy related with erectile dysfunction in non-urologic cancer patients?. Int J Cancer Manag. 2018; 11(9):e82529.

20.

Huang

, Lin

, Yu

, et al. Erectile and urinary function in men with rectal cancer treated by neoadjuvant chemoradiotherapy and neoadjuvant chemotherapy alone: a randomized trial report. Int J Colorect Dis. 2016; 31(7):1349–57.

21.

Mahmood

, Shamah

, Creed

, et al. Radiation-induced erectile dysfunction: recent advances and future directions. Adv Radiat Oncol. 2016; 1(3):161–9.

22.

Mialon

, Berchtold

, Michaud

, et al. Sexual dysfunctions among young men: prevalence and associated factors. J Adolesc Health. 2012; 51(1):25–31.

23.

Nguyen

HMT

, Gabrielson

, Hellstrom

WJG

. Erectile dysfunction in young men—a review of the prevalence and risk factors. Sex Med Rev. 2017; 5(4):508–20.

24.

Acquati

, Zebrack

, Faul

, et al. Sexual functioning among young adult cancer patients: a 2-year longitudinal study. Cancer. 2018; 124(2):398–405.

25.

Sanchez-Cruz

, Cabrera-Leon

, Martin-Morales

, et al. Male erectile dysfunction and health-related quality of life. Eur Urol. 2003; 44(2):245–53.

26.

Caskurlu

, Tasci

, Resim

, et al. The etiology of erectile dysfunction and contributing factors in different age groups in Turkey. Int J Urol. 2004; 11(7):525–9.

27.

Donatucci

, Lue

. Erectile dysfunction in men under 40: etiology and treatment choice. Int J Impot Res. 1993; 5(2):97–103.

28.

Massie

. Prevalence of depression in patients with cancer. J Natl Cancer Inst Monogr. 2004;(32):57–71.

29.

Nicolosi

, Moreira

Jr , Villa

, et al. A population study of the association between sexual function, sexual satisfaction and depressive symptoms in men. J Affect Disord. 2004; 82(2):235–43.

30.

Sugimori

, Yoshida

, Tanaka

, et al. Relationships between erectile dysfunction, depression, and anxiety in Japanese subjects. J Sex Med. 2005; 2(3):390–6.

31.

Chatterjee

, Andrews

, McGarrigle

, et al. Cavernosal arterial insufficiency is a major component of erectile dysfunction in some recipients of high-dose chemotherapy/chemo-radiotherapy for haematological malignancies. Bone Marrow Transplant. 2000; 25(11):1185–9.

32.

Bravi

, Tin

, Montorsi

, et al. Erectile function and sexual satisfaction: the importance of asking about sexual desire. J Sex Med. 2020; 17(2):349–52.

33.

van Anders

. Testosterone and sexual desire in healthy women and men. Arch Sex Behav. 2012; 41(6):1471–84.

34.

Ohl

, Carlsson

, Stecher

, et al. Efficacy and safety of sildenafil in men with sexual dysfunction and spinal cord injury. Sex Med Rev. 2017; 5(4):521–8.

35.

Cohen

. The challenge of erectile dysfunction management in the young man. Curr Urol Rep. 2015; 16(12):84.