3H-thymidine incorporation into mammary carcinoma cells obtained by needle aspiration before and during endocrine therapy

Abstract

3H-thymidine autoradiography was used to evaluate DNA-synthesis in carcinoma cells obtained by fine-needle aspiration biopsy from mammary carcinomas. Needle aspirates were analyzed before and after oophorectomy, and before and during treatment with oestrogen or anti-oestrogen (tamoxifen). Tumor regression occurred in 18 patients-in one of four following oophorectomy, in 15 of 38 treated with tamoxifen and in two of three given oestrogen. Seven tumors remained stationary for long periods-up to a year. In 20 cases there was tumor progression. Regression of tumors was preceded by a decrease in the fraction of 3H-thymidine-labeled cells (s-phase cells). The tumors that remained stationary or progressed retained significant levels of 3H-thymidine incorporation. This study thus showed that 3H-thymidine autoradiography can give an early estimate of tumour response to endocrine therapy. Considerable differences were found between the carcinomas in regard to proportions of S-phase cells. Further insight into this parameter may be useful for planning chemotherapy with S-phase specific agents.

PIP: Variations in DNA synthesis as measured by tritiated-thymidine autoradiography in mammary carcinoma before and during endocrine therapy were studied in patients treated for inoperable or locally recurrent mammary carcinoma. Tumor cells were collected by aspiration biopsy and immediately expelled into the incubating solution. Cell viability was assessed by staining unfixed cells with trypan blue and fixed cells with orecin. To assess viability tritiated-uridine incorporation was used in some experiments. The same cells were identified by each method. Bilateral oophorectomy was done in 4 patients. In the 1 case in which regression followed, a 5-fold decrease in DNA-synthesis was noted 1 week after oophorectomy but at 2 weeks no cells incoporated thymidine. In the 3 patients with tumor progression the fraction of labeled cells was unchanged. For antiestrogen therapy, Tamoxifen (Nolvadex) was used. Serial needle aspirates were collected from 38 patients who received 20 mg of Tamoxifen twice daily. Complete remission followed in 7, incomplete remission in 8, stationary disease in 7, and progression in 16. DNA synthesis fell to very low values after 1-3 weeks and remained low in the 7 cases with complete regression. Tumors showing partial regression showed diminished fractions of 5-phase cells (tritiated-thymidine-labeled cells) after 1-5 weeks. In 1 instance at 72 weeks the S-phase fraction of cells was higher than initial value. Tumor value remained stationary for 40 weeks and then increased. Antiestrogen therapy was stopped at 82 weeks. In those with progressive tumor growth there was high DNA synthesis. Between 20-30% of the cells were replicating DNA. None showed decrease in the fraction of S-phase cells, and 1 showed increase. For estrogen therapy, estradiol valepianate was given im every 2 weeks. Of the 3 patients who received estrogen therapy, 2 of the tumors responded and the DNA-synthesis rapidly decreased until none was measurable after 4 weeks. S-phase values prior to endocrine therapy showed no correlation with the therapeutic response. Tumors that responded showed a decrease in the proportion of S-phase cells during the first 3 weeks. In tumors responding to encocrine therapy the decrease in tritiated-thymidine incorporation was rapid and preceded reduction in tumor size. Data suggest that 2 aspirates should be studied before therapy and repeated after 2-4 weeks in order to include the minimal proportion of S-phase cells. The patients accepted the needle biopsies well. There were no growths of carcinoma at the puncture sites. About 5 weeks must elapse before tumor response can be assessed. Determining hormone receptors in surgically removed carcinoma specimens gives much more rapid indications as to possible response to endocrine therapy.