POORLY DIFFERENTIATED CARCINOMA AND POORLY DIFFERENTIATED ADENOCARCINOMA OF UNKNOWN ORIGIN - FAVORABLE SUBSETS OF PATIENTS WITH UNKNOWN-PRIMARY CARCINOMA

Purpose: The objectives of this study were to assess clinical outcomes and prognostic factors in unselected, consecutive patients with poorl y differentiated carcinoma (PDC) or poorly differentiated adenocarcino ma (PDA). Patients and Methods: The 1,400 patients analyzed were refer red to our unknown-primary tumor (UPT) clinic from January 1, 1987 thr ough July 31, 1994. Clinical data from these patients were entered int o a computerized data base for storage, retrieval, and analysis. Survi val was measured from the time of diagnosis; survival distribution was estimated using the product-limit method. Multivariate survival analy ses were performed using proportional hazards regression and by recurs ive partitioning. Results: Nine hundred seventy-seven patients were di agnosed with unknown-primary carcinoma (UPC) and 337 of these patients held PDC or PDA. No clinical differences were identified among patien ts with PDC, PDA, or UPC patients with other carcinoma or adenocarcino ma subtypes. PDC patients enjoyed better survival than PDA patients. P oor cellular differentiation wets not an important prognostic variable . Variables predictive of survival included lymph node metastases, sex , number of metastatic sites, histology (PDC v PDA), and age. Although chemotherapy did not appear to influence survival for the entire grou p of PDC or PDA patients, a subset of patients with good prognostic fe atures experienced median survival durations of up to 40 months. Concl usion: The long median survival and chemotherapy responsiveness of UPC patients with PDC and PDA could not be confirmed. However, subpopulat ions with prolonged median survival durations could be defined, and th e value of chemotherapy in this group remains to be determined. Identi fication and exclusion of treatable or slow-growing malignancies may a ccount for the poor survival of the PDC and PDA patients reported in t his study. (C) 1997 by American Society of Clinical Oncology.