Pathology of rectal adenocarcinoma following preoperative adjuvant radiotherapy and chemotherapy

The study group comprised 13 patients (mean age 68 years) with clinically f ixed and biopsy proven moderately differentiated rectal adenocarcinoma (8 h igh rectal, 5 low-mid rectal) who received synchronous courses of preoperat ive combination chemotherapy and pelvic radiotherapy (radiotherapy alone in 3 cases) over a period of 8-20 weeks prior to surgical resection, All case s showed varying degrees of mural and mesorectal fibrosis, Three cases did not differ otherwise from usual rectal adenocarcinoma while 4 had a 20-30% diminution in expected tumour area. In 6 cases tumour could not be definite ly identified grossly - 1 showed a 50% reduction in tumour bulk while 5 had only residual microscopic foci from 0.6 - 4 mm in maximum dimensions. Only 3 cases had involvement of the mesorectal circumferential radial margin. F our involved lymph nodes in 2 cases were partially hyalinised and calcified . Preoperative combination adjuvant therapy can produce marked regressive m orphological changes in rectal adenocarcinoma. The implications of this are discussed.