Did GOG99 and PORTEC1 change clinical practice in the United States?

Objective: To assess the practice of adjuvant radiation (RT) for endometrial cancer in the United States following the publication of the Post Operative Radiation Therapy in Endometrial Carcinoma (PORTEC1), and Gynecologic Oncology Group-Adjuvant Radiation for Intermediate Risk Endometrial Cancers (GOG99).

Methods: A retrospective cohort study using the NCI SEER database compared the use of RT pre and post publication of PORTEC1 (1996-99 v 2000-03) and GOG 99 (2000-03 v 2004-07). Criteria for intermediate (IR) and high-intermediate (HIR) risk categories as defined by PORTEC1 and GOG99 were applied. Chi-squared statistics and adjusted multivariable Poisson models were used.

Results: RT did not increase for HIR (RR 1.05, 95%CI 0.99, 1.11) or IR groups (RR 1.0, 95% CI 0.95, 1.05) following GOG99 publication, or for HIR (RR 1.01, 95% CI 0.86, 1.19) or IR groups (RR 0.88, 95% CI 0.77-1.00) following PORTEC1 publication. Radiation rates changed heterogeneously across the country without a discernible pattern of cause. Among radiated patients, brachytherapy use increased, whereas external beam use decreased after GOG99 publication.

Conclusions: As the debate regarding the utility of adjuvant radiation in early stage endometrial cancer continues, we found that overall, clinicians had not adopted GOG99 or PORTEC1 results into their clinical practice in the years immediately after publication. However, we did identify significant variation in practice by geographic location. Given that barely half the women deemed highest risk for recurrence received radiation, these findings illustrate that clinical practice reflects the continued controversy surrounding adjuvant radiation in the treatment of endometrial cancer.