Rationale for different chemotherapeutic and radiation therapy strategies in cancer management

Article Abstract:

For a number of different cancers, including breast cancer, lung cancer, and cancer of the rectum, the use of radical surgery is decreasing and the use of chemotherapy and radiotherapy is increasing. However, there is virtually no reason to believe that the dosage schedules of chemotherapy or radiotherapy have yet been optimized. Furthermore, the clinical protocols for chemotherapy and radiotherapy have evolved independently, and the most appropriate use of chemotherapy and radiotherapy together remains an open question. Toxic effects limit the simultaneous use of chemotherapy and radiotherapy. However, if radiotherapy is postponed until chemotherapy is complete, then there may have been sufficient time for tumor cells to repopulate, limiting the effectiveness of treatment. In a thorough review, the authors discuss the key concepts of chemotherapy and radiotherapy, and suggest methods for improving the effectiveness of combined treatment modalities. They suggest that a promising method of optimizing patient response is alternating the schedule of chemotherapy and radiotherapy. In conventional chemotherapy treatment, cycles of chemotherapy are separated by a three to four week period, which is required primarily for the recovery of the bone marrow and the gastrointestinal system. In the alternating schedule, radiotherapy is given as quickly as possible after the end of a cycle of chemotherapy. In this way, the effectiveness of the chemotherapy is not reduced, but the toxicity is kept within limits by separating the two treatments in time. Indeed, research suggests that one of the most important factors contributing to the success of cancer therapy is the administration of the full dosage of chemotherapy or radiotherapy, and that reductions necessitated by toxic effects are associated with decreased survival. In avoiding dose reductions, the alternating schedule shows promise of improving the outcomes in patients whose cancers are responsive to chemotherapy and radiotherapy. However, clinical trials will be necessary to reliably demonstrate the usefulness of particular protocols of alternating therapy in the treatment of specific cancers. (Consumer Summary produced by Reliance Medical Information, Inc.)

Cancer, Cancer treatment, Chemotherapy

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Treatment of clinical Stage I Hodgkin's disease by local radiation therapy alone: a United Kingdom Childrens Cancer Study Group study

Article Abstract:

The incidence of Hodgkin's disease is very low in young children, but increases with age. In the US, Hodgkin's disease occurs in 5.7 per million children under the age of 15 each year, accounting for about 5 percent of childhood cancers. Since the current treatments for early stage Hodgkin's disease are effective and the survival rate is good, the majority of therapeutic efforts are directed towards reducing the undesirable side effects of treatment. Chemotherapy may cause the development of other cancers, and seriously affects fertility. Whole body irradiation impairs normal growth. To avoid the most serious side effect of radiation for children, an attempt was made to evaluate the effectiveness of radiotherapy limited to the local area of the tumor. Researchers believed there was ample reason to hope for success, since radiation alone has been shown to be effective, and the use of local radiation therapy alone reserves the possibility of using chemotherapy effectively at a later date should the patient relapse. This approach was used in the treatment of 59 children with Stage I Hodgkin's disease. Nine patients relapsed after local radiation therapy at a median of 18 months. Eight of these nine patients were subsequently treated successfully with chemotherapy and remain alive with no evidence of disease. Fifty children required only local radiation and are alive without evidence of disease at a median of three years. The overall survival of 98 percent indicates that local radiation is an effective treatment protocol for Stage I Hodgkin's disease and causes a minimum of adverse effects. However, long-term follow-up of the patients is essential for effective management. (Consumer Summary produced by Reliance Medical Information, Inc.)

Hodgkin's disease, Pediatric diseases, Hodgkin's disease in children

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Primary therapy for limited breast cancer: radiation therapy techniques

Article Abstract:

Early diagnosis has changed the style of treatment for breast cancer. For Stages I and II carcinoma, breast-conserving surgery followed by radiation yields 10-year survival rates of 86 percent, and 20-year rates of 80 percent. While mastectomy gives equal results in terms of survival, breast-conserving treatment is often preferred for the superior quality of life it affords. Estimates suggest that with early diagnosis, three-quarters of all breast cancer patients would be candidates for breast-conserving therapy. Breast-conserving therapy includes radiation to reduce the incidence of recurrence; the recommended total dose is 4,500 to 5,000 cGY (a Gy, or Gary, is 1 joule of energy absorbed per kilogram of tissue). Often the radiation to the breast is supplemented by a boost to the tumor area. The tumor area boost may be achieved using either external radiation or implantation of a radioactive seed into the tumor bed. Patients who have positive lymph nodes in their armpits should receive additional radiotherapy of the mammary and axillary lymph nodes. While some recurrence of tumor in the breast is to be expected, recent studies have indicated that almost 90 percent of local recurrences may be controlled by mastectomy, and that these patients have the same survival rates as those who have not had recurrences. Modern techniques can result in tumor control rates of 90 percent at 10 years with good to excellent cosmetic results in 80 percent of the cases. The best results require coordination of surgeons, radiotherapists, and chemotherapeutic staff. (Consumer Summary produced by Reliance Medical Information, Inc.)

Surgery, Breast cancer

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