Treatment selection for men undergoing curative treatment for prostate cancer is often a challenging decision in view of the goal of maximising cure while maintaining quality of life. Previous quality-of-life comparisons suggest that specific outcomes are associated with type of treatment (surgery vs radiation); however, the functional anatomy approach, starting with nerve-sparing prostatectomy, assumes that quality-of-life outcomes are established by anatomic preservation. Emerging applications of the functional anatomy approach for prostate radiation will ultimately allow for individualised treatments that address the normal tissue variants visible on MRI. Such approaches will encompass all essential functions affected by treatment including genitourinary, rectal, and sexual functions. In this Review, we outline the current techniques in functional anatomy-based preservation related to sexual outcomes, and outline the capacity of vessel-sparing radiotherapy to preserve sexual function in 90% of patients at the 5 year follow-up while maintaining excellent cure rates.