TREATMENT PLANNING FOR PRIMARY BREAST-CANCER - A PATTERNS OF CARE STUDY

Purpose: The 1989 Patterns of Care Study included treatment planning f or early breast cancer. A Consensus Committee of radiation physicists and oncologists determined current guidelines and developed questionna ires to determine treatment planning and delivery processes used by th e participating institutions (e.g., use of portal films). This article presents and analyzes the results of that survey. Methods and Materia ls: The survey included 449 respondents, distributed as follows: 136 ( 30%) from Strata I (academic facilities); 169 (38%) from Strata II (ho spital based facilities); and 144 (32%) from Strata III (freestanding facilities). The treatment planning procedures surveyed included: whet her individualized tissue compensators are used, whether inhomogeneity corrections are used in dose calculations, the use of computerized to mography, whether isodose distributions for external beam tangents and interstitial implants are generated, the use of lymphoscintigraphy, i mmobilization de,ices, simulations, portal films, etc. Results: The su rvey results demonstrated that out of 305 patients from Strata I and I I institutions, 237 (78%) had simulated tangential fields. Consistent with this finding is that 76 % of patients from Strata I and II instit utions mere immobilized, while only 51% of Strata III patients were. M oreover, only 18 out of the 449 (4%) of cases did not have any type of external beam dose distribution calculated-presumably, in these cases missing tissue compensation would be unlikely. On the other hand, 41% of the Strata II, 27% of St ata III, but only 19% of Strata I (p < 0. 0002) cases received CT. Surprisingly, 19% of the Strata I, 35% of the Strata II, and 35% of the Strata III (p = 0.0011) patients received l ymphoscintigraphy, perhaps reflecting the use of wide tangents to enco mpass the internal mammary nodes in these patients. In terms of optimi zing treatments, 74% of Strata I, 70% of Strata II, and 78% of Strata III patients had wedges used on both tangential fields, although in 5, 12, and 14%, respectively, no beam modification of any sort was used. Furthermore, it should be noted that in 7% of the Strata I, 23% of St rata II, and 37% of Strata III cases there was no attempt to reduce th e divergence of the tangential fields into the lung. On the other hand , if one considers the 135 (of 449) patients where matching of the tan gential and supraclavicular fields was applicable, 41% of Strata I, 22 % of Strata II and 46% of Strata III patients had those fields matched in a vertical plane, which would involve sophisticated alignment proc edures. Quality control of treatment delivery was high: 97% of all sur veyed received portal films at least once. The use of thermoluminescen t dosimetry (TLD) to measure the dose to the contralateral breast was of Little interest: only 4 of the 305 Strata I and II patients receive d in vivo measurements. Conclusions: This national survey has establis hed the patterns of treatment planning for early breast cancer. It sho ws a generally consistent approach-although a number of statistically significant variations have been identified. Copyright (C) 1996 Elsevi er Science Inc.