Quantifying the risk of sexual dysfunction in men treated with pelvic radiation therapy for locally advanced rectal...

As the incidence of stage II-III locally advanced rectal cancer (LARC) rises in younger patients, we sought to investigate the risk of sexual dysfunction following radiation therapy (RT) in younger men.

Men ≤50 years old diagnosed with LARC between 1995-2019 at a single institution were retrospectively evaluated. Primary outcomes of erectile dysfunction (ED) and ejaculatory dysfunction (EjD) were defined via ICD codes and clinical evaluation. Cumulative incidences were calculated with death as a competing risk. Subdistribution hazard ratios from competing risk regression models were used. Dosimetric parameters to organs at risk were extracted to suggest dose constraints to prevent sexual dysfunction.

The study included 429 men: 350 received concurrent chemoradiation therapy (CXRT) as part of their treatment, and 79 did not receive RT. The two groups were similar with respect to age at diagnosis, stage, and medical comorbidities associated with sexual dysfunction (p>0.05). With a median follow-up of 6.3 years, the 5-year cumulative incidence of ED in the CXRT group was 25% (95%CI 20-30%) compared to 3.9% (95%CI 1.0-10%) in the no RT group (p<0.001). On multivariable analysis, CXRT maintained statistical significance as an independent risk factor for ED (HR 3.55, 95% CI 1.34-9.44, p=0.011). Within the CXRT group, inguinal coverage in the treatment fields was an independent risk factor for ED (HR 2.38, 95% CI 1.30-4.34, p=0.005), and greater distance from the anal verge had a protective effect. No difference was found in EjD between the 2 groups.

CXRT independently increases risk of ED but not EjD in patients treated for rectal cancer. Technique and target location may impact sexual dysfunction, possibly due to greater radiation dose to the genitalia. These findings may aid in establishing new constraints and promote counseling of young male patients on risks of sexual dysfunction.