Does radiation for prostate cancer cause erectile dysfunction? This is a common concern for men considering radiotherapy as treatment for prostate cancer. Radiation therapy can indeed lead to erectile dysfunction, though the pattern and severity differ from surgical side effects. Between 40% and 70% of men experience some degree of erectile difficulties within two to three years following radiotherapy, with the condition developing gradually rather than immediately. Understanding the mechanisms, risk factors, and available treatments helps men make informed decisions about their care and manage sexual side effects effectively.

Understanding Radiation Therapy for Prostate Cancer

Radiation therapy represents one of the primary curative treatment options for localised and locally advanced prostate cancer in the UK, alongside surgery and active surveillance. The treatment works by delivering high-energy radiation beams to destroy cancer cells whilst attempting to minimise damage to surrounding healthy tissue. Two main types of radiotherapy are commonly used: external beam radiotherapy (EBRT), which delivers radiation from outside the body, and brachytherapy, which involves placing radioactive seeds directly into the prostate gland.

Modern radiotherapy techniques have evolved considerably over recent decades. Intensity-modulated radiotherapy (IMRT) and stereotactic body radiotherapy (SBRT) allow clinicians to target the prostate more precisely, reducing radiation exposure to nearby structures such as the rectum, bladder, and neurovascular bundles responsible for erectile function. According to NICE guidance (NG131), men with localised or locally advanced prostate cancer suitable for radical treatment should be offered a choice between radical radiotherapy (with androgen deprivation therapy when indicated by risk group) and radical prostatectomy, supported by shared decision-making.

The treatment course varies depending on the technique employed. EBRT is typically delivered using hypofractionated schedules (around 20 fractions over 4 weeks) or conventional fractionation (37–39 fractions over 7–8 weeks), whilst SBRT may involve as few as 5 fractions. Brachytherapy monotherapy is generally reserved for low-risk disease and may be delivered as a single procedure; in selected higher-risk cases, a brachytherapy boost may be combined with EBRT. The radiation damages the DNA of cancer cells, preventing their ability to divide and grow. However, this mechanism is not entirely selective, and surrounding tissues—including blood vessels, nerves, and erectile tissue—may also sustain damage.

Understanding how radiotherapy works is essential for patients considering this treatment option. Whilst radiation therapy offers excellent cancer control rates comparable to surgery, it carries distinct side effects that differ from surgical complications. The impact on sexual function develops gradually over time, unlike the immediate effects often seen with radical prostatectomy.

Does Radiation for Prostate Cancer Cause Erectile Dysfunction?

Yes, radiation therapy for prostate cancer can cause erectile dysfunction (ED), though the relationship is complex and develops differently compared to surgical treatment. Observational data suggest that between 40% and 70% of men experience some degree of erectile dysfunction within two to three years following radiotherapy, though rates vary considerably depending on baseline function, radiation technique, use of androgen deprivation therapy (ADT), and individual patient factors. The incidence and severity differ by modality: men receiving EBRT with ADT typically report higher rates than those receiving brachytherapy monotherapy or EBRT alone.

The mechanism by which radiation causes ED differs fundamentally from surgery. Rather than immediate nerve damage, radiotherapy causes progressive vascular injury to the small blood vessels supplying the penis and damage to the cavernosal nerves over time. This radiation-induced damage leads to fibrosis (scarring) of erectile tissue, reduced blood flow, and gradual deterioration of erectile function. Importantly, erectile function may remain relatively preserved immediately after treatment but decline progressively over months to years—a pattern distinct from post-surgical ED.

Observational studies suggest that brachytherapy may be associated with slightly lower rates of erectile dysfunction compared to EBRT, particularly in younger men with good baseline function, though evidence is mixed and influenced by patient selection. Combination therapy (brachytherapy plus EBRT) may increase the risk. Modern techniques such as IMRT and SBRT appear in some studies to reduce ED rates compared to older conventional radiotherapy methods by better sparing the neurovascular bundles and penile bulb, though evidence remains evolving and may be confounded by baseline factors and ADT use.

Androgen deprivation therapy (ADT), often given alongside radiotherapy for intermediate- or high-risk prostate cancer, significantly compounds erectile dysfunction risk. ADT suppresses testosterone production, which is essential for libido and erectile function. Men receiving combined radiotherapy and ADT experience higher rates of sexual dysfunction—including reduced libido and orgasmic function—than those receiving radiotherapy alone. The duration of ADT (typically 6 months to 3 years depending on cancer risk, as per NICE NG131) influences the severity of sexual side effects. Some recovery of sexual function may occur after ADT cessation, though the degree varies. Reduced libido during ADT can also limit the response to treatments for erectile dysfunction.

Risk Factors That Increase Erectile Dysfunction After Radiotherapy

Several patient-specific and treatment-related factors influence the likelihood and severity of erectile dysfunction following radiation therapy for prostate cancer. Understanding these risk factors helps clinicians counsel patients appropriately and may guide treatment selection. Documenting baseline erectile function (for example, using the International Index of Erectile Function questionnaire, IIEF-5) before treatment is recommended.

Pre-treatment erectile function is the strongest predictor of post-radiotherapy sexual function. Men with excellent erectile function before treatment are more likely to maintain adequate function afterwards, whilst those with pre-existing ED are at substantially higher risk of complete erectile dysfunction. Age plays a significant role, with older men (particularly those over 70) experiencing higher rates of ED than younger patients.

Cardiovascular risk factors including diabetes, hypertension, high cholesterol, obesity, and smoking significantly increase ED risk after radiotherapy. These conditions compromise vascular health, making blood vessels more susceptible to radiation damage. Men with multiple cardiovascular risk factors may experience more severe and earlier onset of erectile dysfunction. Certain medications used to manage these conditions—such as some antihypertensive agents and selective serotonin reuptake inhibitors (SSRIs)—may also contribute to erectile difficulties. A medicines review in primary care to optimise management of comorbidities and address modifiable risk factors is advisable.

Treatment-related factors also substantially influence outcomes:

• Radiation dose and field size: Higher doses and larger treatment volumes increase the risk of damage to erectile structures

• Use of androgen deprivation therapy: ADT duration and timing significantly impact sexual function

• Radiation technique: Older conventional techniques may carry higher ED risk than modern IMRT or SBRT, though evidence is evolving

• Penile bulb dose: Higher radiation doses to the base of the penis correlate with increased ED risk; UK radiotherapy planning protocols may include dose constraints to the penile bulb to reduce this risk

Psychological factors including anxiety, depression, and relationship stress can exacerbate physical erectile difficulties. The cancer diagnosis itself, treatment-related fatigue, and concerns about cancer recurrence may all contribute to sexual dysfunction. Partner factors and relationship quality also influence sexual recovery, with supportive relationships associated with better outcomes.

Treatment Options for Erectile Dysfunction After Radiation

Multiple evidence-based treatment options exist for managing erectile dysfunction following radiotherapy, with a stepwise approach typically recommended. Early intervention may improve outcomes, and men should be encouraged to discuss sexual concerns with their healthcare team.

Phosphodiesterase type 5 (PDE5) inhibitors represent the first-line treatment for post-radiotherapy ED. These medications—including sildenafil, tadalafil, vardenafil, and avanafil—enhance erectile function by improving blood flow to the penis. They are effective in approximately 40–60% of men after radiotherapy, though success rates are lower than in the general population with ED. Tadalafil may be prescribed as daily low-dose therapy or on-demand at higher doses. Generic sildenafil is generally available on NHS prescription for men with ED following prostate cancer treatment; other PDE5 inhibitors may be subject to Selected List Scheme (SLS) restrictions or require specialist initiation depending on local NHS funding policies.

Important safety information: PDE5 inhibitors are contraindicated in men taking nitrates (for angina or heart failure) due to the risk of severe hypotension. Caution is required when used alongside alpha-blockers (for benign prostatic hyperplasia or hypertension); dosing should be separated, and blood pressure monitored. Cardiovascular fitness should be assessed before prescribing, as sexual activity carries cardiovascular demands. Common adverse effects include headache, flushing, indigestion, and nasal congestion. Men should be advised to seek urgent medical attention if they experience chest pain or an erection lasting more than 4 hours (priapism).

Vacuum erection devices (VEDs) offer a non-pharmacological option suitable for many men. These devices create negative pressure around the penis, drawing blood into the erectile tissue, with a constriction ring then maintaining the erection. VEDs are effective, non-invasive, and can be used regardless of the cause of ED. Some evidence suggests early use may help preserve erectile tissue health. They may be used alone or in combination with PDE5 inhibitors.

Intracavernosal injections involve self-administering medication (typically alprostadil, such as Caverject) directly into the penis, producing an erection within 5–15 minutes. Whilst this approach requires training and confidence, it offers higher success rates (60–80%) than oral medications. Intraurethral alprostadil (MUSE) represents an alternative delivery method, though it is generally less effective. Topical alprostadil cream (Vitaros) is also licensed in the UK and may be considered. Important safety advice: men using alprostadil should seek urgent medical care if an erection lasts more than 4 hours (priapism), or if they experience severe penile pain or signs of infection at the injection site.

Penile prosthesis surgery may be considered for men who do not respond to other treatments. Inflatable or semi-rigid implants can restore the ability to achieve penetrative intercourse, with high satisfaction rates among carefully selected patients. This option is typically reserved for men who have tried and failed conservative treatments. Referral to urology or andrology services is appropriate for assessment.

Psychological support and psychosexual counselling should be offered alongside physical treatments, addressing the emotional and relationship impacts of sexual dysfunction. Referral to specialist psychosexual medicine or NHS sexual health services may be appropriate for complex cases or when first-line treatments are ineffective.

Reporting side effects: Patients should be advised to report any suspected adverse reactions to medicines or medical devices via the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk or through the Yellow Card app.

Preventing and Managing Sexual Side Effects During Treatment

Proactive strategies may help minimise sexual side effects and optimise recovery of erectile function following radiotherapy. A comprehensive approach addressing physical, psychological, and relationship aspects offers the best outcomes.

Penile rehabilitation programmes involve early and regular use of erection-promoting treatments to maintain penile tissue health and blood flow during and after radiotherapy. The rationale is that regular erections help preserve erectile tissue oxygenation and prevent fibrosis. Evidence for penile rehabilitation remains limited and evolving, and there is no single NICE-endorsed protocol. However, some UK centres offer rehabilitation programmes as part of routine care, involving regular PDE5 inhibitor use (often starting during or immediately after treatment) or vacuum device therapy. Men may wish to discuss this option with their oncology or urology team.

Optimising cardiovascular health before and after treatment may reduce ED risk. Men should be encouraged to:

• Stop smoking: Smoking significantly impairs vascular function and erectile recovery

• Maintain a healthy weight: Obesity is associated with worse sexual outcomes

• Exercise regularly: Physical activity improves cardiovascular health and may enhance erectile function

• Manage chronic conditions: Optimal control of diabetes, hypertension, and cholesterol protects vascular health

A medicines review in primary care can identify and address medications that may worsen erectile function.

Open communication with healthcare professionals and partners is essential. Men should be counselled about expected sexual side effects before treatment begins, with realistic expectations about the timeline and pattern of erectile changes. Regular follow-up appointments should include discussion of sexual function, with proactive referral to specialist services when needed.

Relationship support helps couples adapt to changes in sexual function. Exploring alternative forms of intimacy, adjusting expectations, and maintaining emotional connection can preserve relationship satisfaction even when erectile function is impaired. Couple-based counselling may be beneficial.

When to seek help: Men should contact their GP or oncology team if they experience complete loss of erectile function, significant distress related to sexual changes, or relationship difficulties. Early intervention typically offers better outcomes than delayed treatment. Seek urgent medical care if you experience an erection lasting more than 4 hours (priapism), severe penile pain, signs of infection after intracavernosal injections, or chest pain during sexual activity. Referral to urology, andrology, or psychosexual medicine services is appropriate for men who do not respond to first-line treatments or who have complex needs. NHS sexual health services may also provide support and counselling.

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