Adenoid cystic carcinoma. A clinicopathologic study with flow cytometric analysis.

Forty-five patients with adenoid cystic carcinoma (ACC) of salivary glands were retrospectively studied to determine the prognostic use of DNA ploidy analysis compared with clinicopathologic features. Nuclear suspensions were prepared from 37 of these tumors by the Hedley technique on paraffin-embedded material. The DNA content was analyzed by flow cytometry after propidium iodide staining. Thirty-five tumors were diploid and 2 were tetraploid. Mean survival was 117 and 52 months for the diploid and tetraploid patients, respectively. The median S-phase fraction (Spf) of the 35 diploid tumors was 4.45%. Of the 17 diploid patients who died of disease, there were 11 tumors with high Spf (greater than 4.45%) and 6 tumors with a low Spf (P less than 0.05 chi-square test). The presence of more than 30% of a solid pattern in the tumor was strongly associated with poor median survival in Kaplan-Meier survival curve analysis (P less than 0.05 log rank test). Grade, stage, recurrence, and metastases were also found to be important prognostic factors. Because few tumors were nondiploid, these results suggest that S-phase fraction analysis may be a more useful prognostic indicator than ploidy classification.