Researchers from the department of urology in a hospital in Switzerland who investigated whether chemotherapeutic response to hormone-refractory prostate cancer could be measured via changes in prostate-specific antigen (PSA) found that prostate cancer doubling time may be an auxiliary marker of response to chemotherapy in patients with hormone refractory prostate cancer.
The study was carried out with forty men who had hormone refractory prostate cancer and bi-dimensionally measurable metastases in the lymph nodes or visceral organs. The investigators calculated PSA doubling time among the patients who had a rising PSA during chemotherapy. Patients' objective best response for any of the chemotherapeutic regimens they were taking was partial remission in 6 patients (15%), stable disease in 13 (32%) and progressive disease in 21 (53%). PSA remained stable or decreased in 4 of the 6 patients who experienced a partial remission (67%), in 7 of the 13 who had stable disease (54%) and in only 4 of the 21 who had progressive disease (19%). There was a significant association between PSA and objective response. The pateints' median PSA doubling time was also studied. Among those patients who had a rising PSA, it was 238 days in patients who experienced a partial response, 224 days in those with stable disease and 113 days in patients with progressive disease.
The researchers concluded that this study indicated that PSA doubling time could be used as an auxiliary endpoint for the evaluation of response to chemotherapy in patients with hormone refractory prostate cancer and therefore could indirectly be used to assess response to chemotherapy in patients with bone metastases.