FEMORAL VESSEL DEPTH AND THE IMPLICATIONS FOR GROIN NODE RADIATION

Purpose: To quantify, based on pretreatment computer tomographic measu rements, potential groin node depths, which will aid in optimal treatm ent planning for patients requiring groin node radiation. Methods and Materials: The pretreatment computer tomographic scans of 50 gynecolog ic cancer patients were reviewed to determine the distance of each fem oral vessel beneath the overlying skin surface, as an indicator of pot ential groin node depth. Correlative data regarding height and weight were obtained from patient medical records, and were used to calculate the Quetelet index, defined as (weight in kg)/(height in m)(2). Treat ment parameters of 5 patients who failed prophylactic groin radiation in a recently published study were assessed to determine if underdosag e represented a possible cause of failure. Results: Individual femoral vessel depths ranged from 2.0 to 18.5 cm. When the depths of all four femoral vessels were averaged in each patient, the mean ''4-vessel av erage'' depth for this patient population was 6.1 cm. The median Quete let index for the group was 25.6, and there was a strong correlation b etween femoral vessel depth and patient Quetelet index. Recalculation of doses provided to the 5 patients failing prophylactic groin radiati on in the Gynecologic Oncology Group study showed that all had receive d potential tumor doses < 4700 cGy, with 3 patients being underdosed b y > 30%. Conclusion: While surgery is often indicated in the managemen t of patients with potential groin node metastases, the role of prophy lactic groin radiation should not be rejected. Data from this study ma y aid in the optimal design and implementation of groin node radiother apy.