Importance of tumor morphology for the long term prognosis of rectal adenocarcinoma.

A retrospective review of 149 consecutive potentially curable rectal adenocarcinomas operated on at our institution between 1965 and 1981 was carried out to assess whether tumor morphology influences long term survival. Complete follow-up was available on all patients and extended to 20 years. Data on tumor morphology was extracted from pathology reports and was available in 147 cases (98.6%). Tumors were defined as exophytic (n = 76) when exhibiting a polypoid growth pattern protruding into the lumen at least 1 cm; when lacking such characteristic growth pattern, tumors were classified under the general term of nonexophytic (n = 71). The 5 year survival rate calculated with life table analysis was 80 per cent for exophytic carcinomas and 54.1 per cent for nonexophytic tumors. This difference was verified by logistic regression analysis and proportional hazard technique and is statistically highly significant (P = 0.001). The rate of distant metastases was 29.7 per cent for exophytic adenocarcinoma and 48.6 per cent for nonexophytic tumors (P = 0.02). Although the results did not reach statistical significance, local recurrence of tumor occurred about twice as often in nonexophytic tumors (15.7%) compared with exophytic tumors (8.1%). Thus, we conclude that tumor morphology is an important preoperative prognostic factor for survival and prediction of distant metastasis, and possibly for local recurrence.