Flutamide withdrawal and concomitant initiation of aminoglutethimide in patients with hormone refractory prostate cancer

Hormonal treatment for prostate cancer

For nearly six decades the preferred primary treatment for advanced prostate cancer has been continuous suppression of testicular androgen production by medical or surgical castration. While androgen deprivation is effective in inducing tumour regression in the large majority of cases, essentially all patients will develop progressive disease. In addition androgen deprivation may be associated with a variety of side effects. Thus, strategies that minimise the use of these agents could potentially lower the morbidity and cost associated with the treatment of advanced prostate cancer. In the era of prostate-specific antigen (PSA) testing, hormonal therapy is being used earlier in the course of the disease when the only evidence of recurrent disease is an elevated PSA. These men may survive for many years and thus have the potential for long periods of exposure to hormonal therapy and its side effects. It has been hoped that the development of alternative hormonal interventions might lead to both enhanced antitumour efficacy as well as improvements in side effect profile.

Antiandrogen withdrawal syndrome associated with prostate cancer therapies: incidence and clinical significance

The antiandrogen withdrawal syndrome is a well established phenomenon in prostate cancer. It is widely accepted that a subset of patients will benefit from the withdrawal of antiandrogen or steroidal hormone from hormonal therapy, exhibiting decreasing prostate-specific antigen (PSA) values and clinical improvement. The pathophysiology of antiandrogen withdrawal syndrome is not completely understood, although androgen receptor gene mutations seem to be the likely explanation. Currently, it is not possible to identify the subset of patients whose tumours will respond to antiandrogen or steroid withdrawal. Tumours that will respond may be classified as androgen-independent and hormone-sensitive tumours as opposed to androgen-independent and hormone-insensitive tumours that do not respond. Patients who respond to antiandrogen withdrawal experience approximately 6 months with improved quality of life; however, it is unknown if this translates into prolonged survival. At the very least, antiandrogen withdrawal offers a therapeutic modality that is not associated with adverse effects and improves quality of life even if only for a very limited time. Recent reports suggest that adding a secondary hormonal therapy such as amino- glutethimide, ketoconazole or steroidal hormones may enhance the response rate and prolong response time to the antiandrogen withdrawal syndrome. However, unless there is proof that this secondary hormonal manipulation prolongs survival, maintenance of quality of life is mandatory because of the possible adverse effects from these potent drugs. The fact that about 30% of patients will respond to antiandrogen or steroid withdrawal in hormone refractory prostate cancer must be taken into account in clinical trials of new cytotoxic agents which have been and will be conducted. Cessation of flutamide for at least 4 weeks and, in the case of bicalutamide, even 8 weeks, is mandatory before antiandrogen withdrawal syndrome can be excluded as the cause of decreasing PSA values. The antiandrogen withdrawal syndrome offers another piece of the puzzle of prostatic carcinoma, but at the same time it demonstrates how different advanced prostate cancer cells may react to therapeutic strategies and, therefore, hormone refractory prostate cancer remains a difficult challenge which must be solved in the future.

Secondary hormonal manipulations in hormone refractory prostate cancer

Hormone refractory prostate cancer is clinically heterogeneous, and many patients retain sensitivity to subsequent hormonal manipulations, even after combined androgen blockage. Antiandrogen withdrawal is a mandatory first step. Subsequent treatment with an alternate antiandrogen, adrenal androgen inhibitor (such as ketoconazole), or glucocorticoid may provide both subjective and objective clinical benefit in up to 65% of patients.

Flutamide withdrawal plus hydrocortisone resulted in clinical complete response in a patient with prostate carcinoma

BACKGROUND

Combined androgen blockade (CAB) (medical or surgical castration plus antiandrogen therapy) is considered by many to be the optimal endocrine maneuver for patients with metastatic prostate carcinoma. When progression occurs after CAB, the discontinuation of the antiandrogen is recommended. The authors present a patient that had a clinical complete response to flutamide withdrawal plus hydrocortisone that, at last follow-up, had been maintained for more than 46 months.

METHODS

A 71-year-old man with a positive family history of prostate carcinoma presented in 1989 with urinary frequency and a suspicious digital rectal examination. He was found to have a poorly differentiated adenocarcinoma (Gleason 4+4). He was started on CAB and his prostate specific antigen (PSA) concentration declined from 96 ng/mL to the normal range and was maintained for the next 24 months. In 1991 his PSA began to rise, and reached 64 ng/mL by 1993. The patient was enrolled on a clinical trial that discontinued the flutamide administration and hydrocortisone was initiated.

RESULTS

Physical examination at the time of enrollment was unremarkable. His PSA declined to below the limits of detection after this maneuver and at last follow-up had been maintained there for more than 46 months. In 1995, the patient underwent a repeat biopsy of the prostate and all six tissue cores were negative for carcinoma. At last follow-up in December 1996, the patient had no evidence of disease and was being followed routinely; however, the authors were continuing treatment with testicular suppression (leuprolide) plus hydrocortisone.

CONCLUSIONS

The authors believe the residual androgens and steroids produced by the adrenal cortex play a meaningful role in prostate carcinoma cell proliferation. Based on this case and data from trials supporting the activity of flutamide withdrawal plus adrenal suppression, it appears reasonable to evaluate prospectively the discontinuation of antiandrogen versus antiandrogen withdrawal plus adrenal suppression in individuals failing CAB.