Positive emission tomography for evaluating a complete clinical response in patients with ovarian or peritoneal carcinoma: correlation with second-look laparotomy.
OBJECTIVE: Positive emission tomography (PET) provides a novel means of imaging malignancies. The following study was undertaken to evaluate the predictive value of PET in determining a pathologic complete response in patients with advanced ovarian or peritoneal carcinoma who had a complete clinical response following primary chemotherapy. METHODS: Twenty-two patients with advanced-stage ovarian (N = 17) or peritoneal (N = 5) carcinoma who had achieved complete clinical and radiologic remission and normal CA-125 level after six cycles of chemotherapy and who had consented to a second look laparotomy procedure were studied. All patients received platinum based therapy and all but one patient, treated elsewhere, received paclitaxel in combination with platinum. Following IV administration of 20 mCi [(18)F]fluorodeoxyglucose (FDG), the entire abdomen and pelvis were scanned. Various technical modifications including bladder activity dilution, intravenous hydration with diuretic therapy, and mechanical bowel preparations, were used to reduce background activity. Second-look laparotomy findings were classified as negative, macroscopically positive if a biopsy of a suspicious area was histologically positive, or microscopically positive if only a nonsuspicious area was histologically positive. The effect of patient preparation prior to PET imaging was evaluated. RESULTS: Persistent disease was found in 13 of the 22 patients (59%). Only one of nine sites with macroscopic and none of four with microscopic disease were accurately predicted. The sensitivity was only 10% and the specificity 42%. Intravenous hydration, diuretic therapy, and bowel preparation did not improve the results. CONCLUSIONS: These results suggest that despite technical modifications the sensitivity of PET before second-look laparotomy for small-volume persistent disease is low.