Patterns of care study for postmastectomy radiotherapy in Japan: Its role in monitoring the patterns of changes in practice

Abstract

Background: Three prospective randomized clinical trials (RCT) in the 1990s demonstrated the survival benefit of postmastectomy radiotherapy (PMRT) for patients with locally advanced breast cancer. The present study was performed to evaluate whether the Patterns of Care Study (PCS) fulfills a role in monitoring the patterns of changes in clinical practices in Japan. Methods: The first survey (JPCS-1) involved 79 Japanese facilities by two-stage cluster sampling of facilities and patients, and was carried out during 1998-2000. JPCS-1 included 1124 patients with breast cancer who were treated between 1995 and 1997. The second survey (JPCS-2) was carried out during 2001-2003, involving 827 patients who were treated between 1999 and 2001 in 76 facilities. Results: Patients with adverse risk factors, including pathologically axillary positive nodes (≥4) and/or advanced primary disease (pT3-4) accounted for 57% of the patients who received PMRT in JPCS-1 and 72% of those in JPCS-2 (P = 0.039). The multiple radiotherapy target volume including the chest wall and regional lymph nodes was applied in 18% of the patients in JPCS-1 and 44% of those in JPCS-2 (P < 0.001). However, the dose distribution was calculated in only 42% of the patients in both surveys (P = 0.467). Conclusions: The eligibility and the target volume for PMRT were influenced by the outcome of RCT, but the quality of radiotherapy did not improve sufficiently. The PCS survey is useful to monitor the changes in patterns of clinical practice and can clarify some problems with radiotherapy techniques. © 2006 Oxford University Press.