Is aryl hydrocarbon hydroxylase activity a new prognostic indicator for breast cancer?

Aryl hydrocarbon hydroxylase (AHH) activity was measured in the breast tumours of 153 primary and 17 recurrent cancer patients, and in 18 patients with benign breast tumour. All operations were carried out in 1983-84. The cytosolic fraction was collected for steroid receptor determination, and microsomes were separated for AHH assay from the same tissue samples. The AHH distribution was wide and highly skewed in all groups. About 10% of the samples showed activities below detection limit. The medians and ranges for primary cancers were 34 (less than 5-2683), for recurrent cancers 40 (20-239) and for benign tumours 11 (less than 5-37) fmol min-1 mg-1 protein. After logarithmic transformation, the mean AHH activities of cancer samples differed significantly from those of benign tumours. The logarithm of AHH activity (log AHH) correlates positively with axillary lymph node status, and negatively with steroid receptor levels. The development of the disease and the survival of the patients were followed for 4 years. The survival and the disease-free interval of the cancer patients who had low AHH activity was significantly higher than that of the high AHH group. The multivariate analysis with Cox's proportional hazad model showed primary tumour size, progesterone receptor concentration, nodal status and log AHH to be the most important independent prognostic factors for survival, while the occurrence of metastases, log AHH and tumour size were the equivalent factors for the disease-free interval in primary breast cancers. We conclude that AHH activity may reflect the overall malignant potential of breast cancer tissue.