Patterns of care study: Hodgkin's disease relapse rates and adequacy of portals.

The Patterns of Care Study (PCS) has noted differences in stage adjusted relative relapse rates for Hodgkin's disease in four large facilities; the rates vary from 0% to 11% for infield or marginal recurrence (P = 0.003), and from 10% to 39% for any relapse (P = 0.0006) among these facilities. These differences in outcome were not attributable to variation in patient workup, treatment method, or radiation dose. A resurvey of 181 of these records of patients treated with radiation therapy for cure, in which portal films were available for review, indicates that treatment portal films did not encompass the disease adequately in 66 patients. When this occurred, there was a 50% overall relapse rate with 32% recurrence either infield or marginal. Chemotherapy tended to obscure the effect of inadequate technology, and when the 26 patients receiving chemotherapy as part of their initial treatment were excluded, inadequate margins were followed by even higher rates of relapse. For the subgroup of patients treated with radiation therapy alone, inadequate margins were associated with a 54% overall relapse rate, of which 33% were infield or marginal recurrence. When the portal films for patients treated with radiation therapy only were judged to be adequate, the total rate of any relapse was 14%, with 7% infield or marginal recurrence. PCS data indicate there is a critical need for accurate inclusion of Hodgkin's disease in the treatment portals; that marked facility differences exist in this technical process; and that skilled independent observers can reliably identify inaccurate technical performance.