| [ Summary ] |
Approximately 80％ of anal canal cancers in our study were squamous cell type and thus radiosensitive compared to rectal adenocarcinoma. Incidence of this condition is low, but has increased recently. Roughly 80％ of anal canal cancer is confined within the pelvis when diagnosed. Concerning the prognostic factors for this condition, tumor size, lymph node metastasis, and the HPV infection affect prognoses. In Western countries the treatment of choice for squamous cell anal canal cancer has been chemoradiotherapy for the past 20 years because it provides sphincter preservation. On the other hand, in Japan, until quite recently, surgery has been the treatment of choice. The chemotherapeutic regimen of choice has been 5-FU＋ Mitomycin C concurrently with 55 Gy to 60 Gy of irradiation. Five-year survival rates have been 50 to 80％, and anal sphinchter preservation rates have been around 70％. In relation to acute toxicity, intestinal and genital skin toxicity are quite common. However, late onset toxicity is infrequent. Patterns of failure are primarily local and thus salvage surgery, whenever possible, is indicated. To improve therapeutic ratios, sophisticated radiotherapy techniques, such as intensity modulated radiation therapy, and newer chemotherapeutic drugs, such as S-1, have been tested with some promising results. Chemoradiotherapy for squamous cell carcinoma of the anal canal is promising, providing good survival rates, good quality of life and acceptable levels of toxicity. |