Proceedingsofthe32ndAnnualASTRO Meeting 99

205

PRACTICAL TOPOGRAPHIC ANATOMY FOR RADIATION THERAPY

Guy J.F. Juillard, M.D.

Department of Radiation Oncology, UCLA Center for Health Science, Los Angeles, CA 90024

A number of reliable anatomic landmarks that are of interest to the radiation oncologist will be presented and discussed.

The knowledge of these landmarks can save time and overcome the need to obtain radiographs during treatment planning, and external landmarks are most helpful for clinical set-ups in emergency radiation therapy situations that often occur after hours when minimal technical help is available.

Particular attention will be given to the head and neck area and its variety of custom shaped fields, and the treatment of breast cancer and Hodgkin's disease with emphasis on projection of lymph nodes. In addition, a rapid review of the anatomy of other areas of the body will be addressed.

Discussion will follow, and participants will have an opportunity to share their experience.

206

CAUSES OF FAILURE IN THE RADIATION THERAPY OF HEAD AND NECK CANCER

Lester J. Peters, M.D. and Gilbert H. Fletcher, M.D.

Division of Radiotherapy, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030

Review of potential causes of failure of radiotherapy for head and neck cancers provides a framework for discussion of a variety of tumor-related, host-related, and technical factors determining radiocurability. This refresher course will consist of a review of theoretical concepts and experimental data (supported by illustrative examples from everyday clinical practice) underlying the following potential causes of failure: inherent cellular radioresistance, volume of cancer, tumor cell hypoxia, tumor cell regeneration, failure of redistribution, delayed tumor regression, radiation dose and fraction size, shape of dose response curve, geographical miss or underdosage, and second primary tumors occurring in the irradiated volume. Emphasis will be place on causes of failure that can be minimized by application of concepts and techniques readily available to all radiotherapists? and on those that provide the hasis of new treatment strategies based on the radiobiological characteristics of individual tumors.

207 CANCER OF THE BREAST - PRIMARY IRRADIATION

Barbara L. Fowble, M.D. and Robert L. Goodman, M.D.

Departments of Radiation Therapy, University of Pennsylvania School of Medicine and The Fox Chase Cancer Center, Philadelphia, Pennsylvania 19104

In the last 10 years both prospective randomized clinical trials and retrospective series have established the role of conservative surgery and radiotherapy as an alternative to mastectomy in the treatment of early breast cancer. This presentation will review the available data from these studies. Points of discussion will include the role of patient selection (patient age, tumor size and nodal status, histology and mammographic findings), the extent of the surgical procedure in the breast (incisional versus excisional biopsy, wide excision versus quadrantectomy), the role of re-excision, the assessment of surgical margins and their significance, the role and extent of the axillary staging procedure, the extent of radiotherapy (breast versus breast and regional node irradiation), and the role of the boost. Each of these issues will be addressed and current treatment policies and recommendations will be outlined. Local recurrence rates and predictors of breast recurrence will be discussed. The ability to combine adjuvant chemotherapy with primary radiotherapy for patients with histologically positive axillary nodes will be reviewed in terms of selection and sequencing of agents, the ability to deliver optimal doses of chemotherapy and the effect of chemotherapy on cosmesis and complications. Long term effects of radiation therapy will be discussed including the incidence of contralateral breast cancer and second malignancy. Mammographic changes post radiation will be presented. Future and ongoing trials will be reviewed including a renewed interest in the omission of breast irradiation in selected patients after wide excision only. Data relevant to this approach will be presented. Finally, the role of conservative surgery and radiotherapy in the treatment of non-invasive intraductal breast cancer will be presented.