There are a number of studies which use chemo adjuvant with HT and which show significantly extended survival times.
For example, look at this set of slide from Eisenberger at Hopkins (it is difficult to follow, since the speech is not there, but you can get a general idea.) www.urotoday.com/images/pdf_files/07.Eisenberger.ChemoRisk.pdf
Look at page 20-21 in particular. It describes a study of "high risk" patients where some were randomized to receiving adjuvant HT only, and some were randomized to adjuvant HT plus Mitoxantrone, a chemotherapy treatment.
Page 21 shows the results: media survival of 80 months for the ones who got chemo vs. 36 months for the other group. At 8 years it looks like 40% of the ones receiving chemo were alive vs. 15% of the other group.
Other studies show similar gains with chemo used in conjuction with HT, as best I can decipher the PPT.
Here's another article you might want to look at: Early Chemotherapy in Prostate Cancer: Adjuvant Chemotherapy After Surgery or Radiotherapy
Nat Clin Pract Urol. 2008;5(9):486-493. © 2008 Nature Publishing Group
David Mazhar, Addenbrooke’s Hospital, Cambridge, England
Jonathan Waxman, Hammersmith Hospital, London, England
(I realize you're past the adjuvant stage, but still the fact that it's helpful there is encouraging) Summary
A considerable proportion of men with clinically localized prostate cancer are not cured by surgery or radiotherapy, and hormone therapy for advanced disease is also not curative. Given the demonstrable efficacy of chemotherapy in hormone-refractory disease, there is an interest in examining the curative potential of chemotherapy when administered early in the natural history of prostate cancer. It is hoped that chemotherapy could be used with hormone therapy and in the adjuvant setting, as is the case in many other solid tumors, in patients with 'high-risk' prostate cancer who are undergoing primary radical prostatectomy or radiotherapy. Early phase clinical trials have shown that using docetaxel as neoadjuvant or adjuvant therapy is safe and feasible. In the neoadjuvant setting, tumor shrinkage, serological response, there is some evidence of pathological downstaging. Several randomized trials are ongoing, and it is anticipated that the results of these studies will help to identify whether the early use of chemotherapy in early prostate cancer is beneficial.
In particular, note this section:Chemotherapy in Hormone-refractory Prostate CancerStudies in the past few years have highlighted the value of chemotherapy in progressive prostate cancer. In the 1990s, Tannock et al. conducted a study in which patients with hormone-refractory prostate cancer were randomly assigned to receive either mitoxantrone and prednisone or prednisone alone. This study showed improvement in patients' quality of life after combination therapy with mitoxantrone and prednisone, although this treatment regimen did not prolong survival -- the median survival of patients in both treatment groups was 10 months.
The treatment options for patients with prostate cancer have changed recently. In October 2004, two publications in the New England Journal of Medicine indicated that the survival of patients with progressive prostate cancer could be improved with docetaxel chemotherapy given in combination with either steroids or with additional cytotoxic therapeutic drugs.[2,3] In these two large studies, patients who received docetaxel chemotherapy had a median survival of 18.9 months from initiation of treatment compared with 16.5 months in patients who received mitoxantrone chemotherapy. This difference represents a significant extension of life. Many authors have compared the survival data from these patients treated with docetaxel with results obtained in Tannock and colleagues' 1996 mitoxantrone study, and have suggested that the advantage of docetaxel in the more recent studies might be understated. Others have commented that the survival time of 16.5 months in patients who received mitoxantrone, as compared with 10 months in the original mitoxantrone study, is an indication of better palliative care. Regardless of this comment, the use of docetaxel chemotherapy certainly represents a substantial advance in the treatment options for patients with prostate cancer, and has become the standard of care for patients with hormone-refractory disease.
Clinicians are now becoming interested in moving docetaxel treatment into earlier stages of prostate cancer. Randomized phase III trials are underway examining the role of docetaxel in patients with locally advanced or metastatic disease who are starting or who have just recently started hormone therapy. Patients are usually better candidates for cytotoxic therapy at this stage of cancer than when their disease becomes hormone refractory. Patients with localized disease and high-risk features in neoadjuvant and adjuvant settings also present opportunities for study. There are currently models of an integrated approach to management for several other malignancies, such as breast and colon; can this combination method also be applied to prostate cancer?
My interpretation of all this is that using chemo after failure of HT seems to only provide a few more months of life, but using chemo in conjunction with HT an early stage could provide a much bigger benefit, including a greatly increased chance of additional years of life. That said, I have not made a detailed study of this, and there could be many considerations in addition to the ones I have found.