Hemibody Irradiation in Advanced Prostatic Carcinoma

Tolerance of half-body irradiation as systemic therapy for patients with locally advanced breast cancer

BACKGROUND

Locally advanced breast cancer (LABC) is one of the main causes of cancer death among women in Bulgaria. In 1988, when this study started, there was still controversy about the role of chemotherapy in controlling systemic disease. There were encouraging results from the Radiation Therapy Oncology Group (RTOG) 82-06 study suggesting that half-body irradiation (HBI) should be used earlier in the disease course to prevent the development of metastases. There were many patients with LABC requiring treatment, but there was a problem with obtaining the drugs needed; they were expensive and not consistently available.

PROCEDURE

Taking into account the medical contraindications to chemo-therapy treatment, its toxicity, and the possibility of chemoresistance, we initiated this study to look at the effects of HBI given as two fractions of 4 Gy to the upper and then lower parts of the body, after surgery and before local radiotherapy.

RESULTS

The acute tolerance of this regimen in 36 patients with LABC was as good as it was in 4 additional LABC patients with M1 disease, and hematologic recovery was satisfactory.

CONCLUSIONS

We conclude that systemic treatment with HBI is tolerable. It therefore may be a convenient and cost-effective treatment for LABC, although better treatments are still needed.

Hormone refractory disease

Hormone refractory disease is observed in less than 20% of newly diagnosed cases of advanced prostatic cancer. In the majority of cases, hormone refractory disease appears after a median time of 18 months of endocrine manipulation and is attributed to the selection and/or cloning of pre-existing or de novo appearing hormone-independent or resistant cell lines. There are no generally accepted rules for second-line management. The varying sets of criteria used by different study groups make comparisons of widely different regimens very difficult. Actually, it seems reasonable to consider length of survival as the only objective response criterion. This implies, however, that there should be an unanimous definition about the moment of primary treatment failure. Indeed, the detection of hormonal escape is a gradual event and the relative length of survival time depends on the chosen moment of therapy administration. To date, monitoring of prostate specific antigen (PSA) has become the best and primary tool to document progression of disease. Earlier diagnosis based on a rise in PSA levels in patients that are still asymptomatic with a good performance status, might provide the opportunity to treat patients that could profit from therapy and give a fair chance to the investigated drug to show efficacity and tolerability. In this paper we will discuss the rationale of the current available second-line therapeutic options in relapsed prostatic cancer.

An overview of current clinical experience with strontium-89 (Metastron)

Prostate cancer is one of the most common tumors in men. At presentation, 50% of patients have advanced disease and 25% have bone metastases. Hormonal palliation is the treatment of choice for metastatic bone pain, with a pain-free response rate of 75% for a period of 16-18 months. Second-line treatment with chemotherapy has a moderate and short-term effect. Once endocrine therapy and chemotherapy cease to be effective, radiotherapy is a good option for recurrent painful bone metastases. Diffuse painful metastases can be treated with half-body irradiation with a response rate of up to 70%, but there is considerable toxicity. Strontium-89 (Metastron) is a calcium analog radionuclide that is selectively absorbed at bone locations with increased osteoblastic activity. It is a pure beta-emitter with bone penetration of 0.8 cm, and it has been used in multiple trials with response rates of up to 80%. Results are reported with Metastron in 28 patients with diffuse painful bone metastases, in whom a response rate of 82% was seen.

Management of relapsing disease in prostate cancer

Almost all patients with prostatic cancer will eventually escape the control of the first-line endocrine therapy and relapse. This escape is attributed to selecting and/or cloning preexisting or de novo appearing hormone-independent or resistant cell lines and occurs in most patients after a median time of 12 to 18 months. Currently, there are no generally accepted rules for second-line management, either endocrine or by other means. It seems reasonable to consider length of survival as the only objective response criterion and not to rely on other response criteria. Available second-line therapeutic modalities in relapsed prostatic cancer are alternative endocrine manipulations, chemotherapy, combined endocrine and cytotoxic therapy, new drugs, radiation therapy, and general antitumoral and supportive care. Second-line therapy in relapsed disease makes sense if life can be prolonged while relieving symptoms and maintaining or improving the quality of survival. The capacity to prolong survival is limited. As a result, second-line therapy should aim more at improving the quality rather than the length of survival while considering the specific expectations and wishes of the patient.