Prostate news article, May 2005
| IF THE PSA RISES
AFTER TREATMENT
Professor Roger S Kirby Visiting Professor to St George's Hospital, London |
 |
Prostate cancer, like its sister breast cancer, is sometimes a difficult tumour to cure. Around one third of all men undergoing removal of the prostate (radical prostatectomy) experience a rise in the PSA marker eventually, and the relapse rate after external beam radiotherapy is even higher. The risk factors for recurrence include an initial PSA of more than 10 ng/ml, a tumour which looks aggressive when examined under the microscope (ie a high Gleason score) and a tumour which extends to the edge of the excised prostate when examined by the pathologist (surgical margin).
PSA recurrence after radical prostatectomy is usually defined as two consecutive rises above a value of 0.2 ng/ml. The timing of this observation is critical because an early and steep rise of PSA may indicate the presence of bone or other secondaries (metastases), which will require treatment by hormone therapy to reduce androgen stimulation of the cancer (usually with 3 monthly injections of ZoladexTM or ProstapTM). A progressive PSA rise a year or more after surgery is more often associated with recurrence of tumour in the vicinity of the excised gland (the prostate bed) though this may be difficult to demonstrate on MRI scanning or ultrasound-guided biopsy. A six week course of radiotherapy which involves 10 or so minutes of treatment per day is effective in 85% of cases, but may cause troublesome side effects of diarrhoea and rectal bleeding, however these are usually temporary. In general the PSA value declines to less than 0.2 ng/ml within a few months of treatment and remains below that value. A subsequent rise is usually an indication for hormone treatment, which, provided a bone scan confirms that no bone metastases are present, can be accomplished with the anti-androgen CasodexTM at a dose of 150 mg/day. This tablet rapidly reduces the PSA, but does cause breast swelling and tenderness in the majority of patients. This may be minimised, either by irradiation of the breast buds prior to treatment or by taking the oestrogen receptor blocker tamoxifen at the same time as the CasodexTM.
Two consecutive PSA rises after external beam radiotherapy is also suggestive of a failure of primary therapy and indication for second line treatment. Since the prostate remains in situ, a biopsy of the gland is usually performed, which may confirm the presence of residual cancer. Bone and MRI scans are usually negative. In this situation, a choice of treatment exists: salvage radical prostatectomy can be technically difficult and carries a significantly greater risk of urinary incontinence compared with the operation in an un-irradiated patient, but can be curative. Recently cryotherapy has been advocated, however care must be taken not to damage the rectal wall as a fistula (an abnormal connection) between the bladder and rectum may result, which requires complex surgery to repair. Hormone therapy with, for example, ZoladexTM or CasodexTM is almost always effective in reducing the PSA but it does not completely eradicate the disease and has a negative impact on sexual function.
Of late, evidence has been accumulating that there exists a group of men who are more likely to suffer PSA recurrence after either surgery or radiotherapy who can be predicted on the basis of their PSA, Gleason score and surgical margin status. In these high risk individuals there may be a case for employing supplementary therapy - either radiotherapy or hormone treatment - with a view to preventing or delaying the rise in PSA. Trials are currently evaluating this more pro-active approach. This has already been shown to be effective in breast cancer, and also seems likely to be the way ahead in a selected subset of men with prostate disease.
Article appearing in the Spring 2005 issue of UPDATE - the newsletter of this charity.