Omission of parametrial boost does not compromise local control, survival in modern era

Leaving out the use of external beam parametrial boost (EBPB) for locally advanced cervical cancer does not seem to negatively affect local control or survival in the era of image-guided brachytherapy, results of a study have shown. This then supports a reduced need for standardized use of parametrial boost.

In this study, the authors identified 100 women with cervical cancer involving the parametria (clinically or radiographically) diagnosed between 2001 and 2017, with a median follow-up of 26.8 months. They also obtained clinicopathologic and treatment features, survival, and patterns of failure data.

The association of these variables, including parametrial boost, with local failure-free and overall survival were assessed by conducting univariate and multivariable data analyses. Finally, competing risks analysis was carried out to evaluate the cumulative incidence of local failure, with death and other features treated as competing events.

Of the identified women, 41 (41 percent) received EBPB, and these patients were less likely to have received magnetic resonance imaging (MRI), positron emission tomography (PET), interstitial, or high-dose rate brachytherapy.

MRI, PET, dose rate, and treatment were strongly associated with survival (Cramer’s V, 0.43–0.68; p<0.01). For the entire cohort, 2-year overall survival was 78 percent and local failure 12 percent.

Multivariable analysis revealed that the use of EBPB was not predictive of any outcome, but treatment year after 2009 was significantly associated with improved outcomes in all models.

“Historically, EBPB has been used in locally advanced cervical cancers to supplement radiation dose. However, it has become controversial in the era of image-guided brachytherapy. Modern 3D imaging and brachytherapy techniques have improved delineation and coverage of tumour,” the authors said.