Oncology, urology  

Combination of radiation therapies more effective treatment for prostate cancer

27 October 2006

Leipzig, Germany. Prostate cancer is the most common tumour in men. In Germany alone, about 48,000 patients develop the disease every year. The PSA test is the standard test to detect signs of the cancer and determine methods of treatment, which can be based on surgery or radiation therapy.

Studies presented at the 25th Annual Congress of the European Society for Therapeutic Radiology and Oncology (ESTRO) appear to show that a combination of different radiotherapeutic methods are able to increase the efficacy of radiation for prostate cancer at an early stage. Experts also report that patients with prostate cancer benefit from a combined hormone and radiation therapy if they have a high risk of disease progression.

Since a simple blood test to detect the "prostate-specific antigen" (PSA) can provide first indications of the presence of the disease, a growing number of tumours are nowadays diagnosed at an early stage. In small tumours limited to the prostate, radiation therapy is an alternative to an operation. In locally advanced tumours, which have passed beyond the limits of the organ and cannot be operated, radiation is the treatment of choice.

External radiation is the standard

The standard method of the radiation therapy is radiation from the outside. However, radiooncologists increasingly apply the so-called brachytherapy. In this method, the physician places a radiation source directly into the prostate. Radiation sources are, on the one hand, small radioactive pins ("seeds") that remain in the prostate and radiate the tumour over a longer time period with a low dose. In the so-called after-loading procedure, hollow needles are stuck into the prostate for a few minutes in one or several sessions. They deliver a defined radiation dose and are then removed again.

Peter Hoskin from the Cancer Centre of the Mount Vernon Hospital in Northwood, UK, presented a study at the ESTRO conference, in which his team tested whether a combination of brachytherapy and external radiation therapy can improve the treatment results for small tumours. To this end, the radiooncologists assigned 220 patients randomly to two groups.

The patients of one group only received an external radiation therapy at the usual dose. The patients of the other group were treated with a lower dosed external radiation therapy, followed by two brachytherapy sessions.

The result

The side effects of the therapy were comparable in both groups. However, the physicians observed differences in the course of the PSA values: In 80% of the patients who had received a combined therapy, the values of the tumour marker remained unchanged during the three-year follow-up period — a sign that the treatment was effective and the disease is under control. In the group of patients who were only externally radiated, this was the case only for 63.6% of them. While final statements are not yet possible due to the short follow-up period, the results indicate, in the specialists' opinion, that the combination treatment is especially effective.

If a prostate tumour can no longer be completely removed or destroyed by surgery or radiation, physicians attempt to inhibit the tumour growth - and thus the progression of the disease - with a drug-based hormone blockade. This is because male sexual hormones stimulate the growth of a prostate tumour.

Promising combination

For some years, physicians have been testing whether a combined therapy of hormone blockade and radiation therapy can also improve the healing chances for prostate cancer in general. Thomas A. Pickles (Vancouver, Canada) presented a study at the ESTRO conference in Leipzig on October 10, in which such a combination treatment was compared to a conventional radiation therapy.

During their study, the physicians split the currently common three risk groups for prostate cancer (high, medium, low) even further into a total of five different risk groups, in order to get a more differentiated picture.

A total of 1835 patients participated in the study. They received either only a radiation therapy or a combination of radiation therapy and hormone blockade. As reported by Pickles, the men of the two lowest risk groups had no significant benefit from an additional hormone therapy. The results were different in the three groups with higher risks: In the group with the highest risk, the PSA values were unchanged in 45 percent of men who had received a combination therapy - an indication that the treatment had been effective. In contrast, only 17 percent of high-risk patients who were only radiated still showed stable PSA values after five years.

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