Anal submucosal injection: methotrexate concentration in rectal tumor tissue and serum after anal compared with parenteral injection.

Abstract

As the results of adjuvant chemotherapy in the treatment of advanced rectal cancer are unsatisfactory, more effective regimens and routes of administration are being tried. Submucosal anal injection of methotrexate (MXT) has given encouraging results in the treatment of pelvic malignancies. This communication studies the MXT level in serum and rectal cancer tissue after either anal submucosal or parenteral MXT administration. Twenty four patients, mean age 46.4 years (16 men and eight women), with stage C rectal cancer were divided into two equal, age- and sex-matched groups. MXT (50 mg) was administered to each patient intravenously in one group and into the anal submucosa in the other. A blood sample was taken 30, 60 and 120 min after injection, and again after 24 h. A tumor sample was also taken each 30 and 60 min of injection. The serum and tissue MXT levels were determined using a radioimmunoassay kit. The serum MXT concentration was significantly higher after parenteral than after anal injection. Meanwhile, the concentration of MXT in tumor tissue was higher after anal administration. In conclusion, the anal route of administration of MXT, by inducing a high MXT concentration in the tumor tissue associated with a low serum level, might achieve satisfactory therapeutic results in advanced rectal cancer, with minimal side effects.