Anatomy of the Anus, Risk Factors, and Anal Cancer Epidemiology in Costa Rica

The anus is the terminal portion of the digestive tract and plays a vital role in waste elimination and continence. Anatomically, it extends from the anorectal junction—located at the level of the puborectalis muscle—to the external anal margin. Its boundaries are well defined: the upper limit corresponds to the dentate line, marking the transition from rectal mucosa to squamous epithelium; the lower limit includes the perianal skin. This region contains important muscular structures such as the internal and external anal sphincters, which allow for voluntary and involuntary control of defecation.

Anal cancer is a malignancy that specifically affects this anatomical area. While less common than other gastrointestinal cancers, its incidence has been rising, particularly in certain at-risk populations. The main risk factors include infection with high-risk types of human papillomavirus (HPV), receptive anal intercourse, smoking, immunosuppression (such as in people living with HIV), and a history of anal or cervical dysplasia.

In Costa Rica, data from the National Cancer Registry indicate that the province of San José has the highest incidence of anal cancer. This may be related to greater urban concentration, improved access to diagnostic services, and sociocultural factors.

Treatment for anal cancer has evolved significantly in recent decades. Thanks to advances in Radiation Oncology, curative treatment can now often be achieved without disfiguring surgery. A combined approach using radiation therapy and chemotherapy has shown excellent results in local tumor control, while preserving anal function and improving patients’ quality of life.

Dr. Rolando Loría Ruiz, a Radiation Oncologist in Costa Rica, is a leading figure in the treatment of this condition. Through his website, www.drrolandoloria.com, he offers the public reliable, easy-to-understand information about anal cancer, including prevention, early detection, and treatment options.

Health education and early diagnosis are essential to improving patient outcomes. Consulting with a specialist in a timely manner can make a meaningful difference in both treatment success and overall quality of life.