The addition of interstitial needles to intracavitary applicators in the treatment of locally advanced cervical cancer: Why is this important and how to implement in low- and middle-income countries?

Abstract

Purpose: Cervical cancer is the leading cause of cancer mortality of women in low-/middle-income countries. Interstitial needles improve outcomes but require resources beyond those available in endemic regions. We conducted a retrospective review of the use of interstitial needles in locally advanced cervical cancer and simulated both 3D planning without needles and 2D planning to explore the benefit of interstitial needles.

Methods and materials: 57 brachytherapy plans of 17 patients who had intracavitary tandem and ring plus interstitial brachytherapy were reviewed. Prescribed dose was 7 Gy × four fractions. 2D plans prescribed to point A were generated to represent a standard Manchester loading. Dosimetric outcomes to clinical target volume and organs at risk (OARs) were compared with those of 3D-based plans.

Results: High-risk clinical target volume coverage was excellent: 93.2% for 2D plans, 93.9% for 3D plans without needles, and 96.2% for 3D with needles. The mean dose to 90% of target was 8.5 Gy/fraction for 2D plans, 7.5 for 3D without needles, and 7.9 Gy/fraction for 3D with needles. However, the 2D plans delivered 12% above recommended dose constraints for OARs (except rectum). Dosimetric differences were found between 3D planning and 3D with needles for target coverage (p = 0.002). Dose to OARs was significantly lower when 3D plans with needles were compared with 2D plans.

Conclusions: Interstitial needles provide an optimal therapeutic ratio for patients with high-volume disease or/and unfavorable topography. This justifies additional capital investment in resources for implementation to provide optimal treatment for locally advanced cervical cancer globally.

Keywords: 3D planning; Brachytherapy; Cervix cancer; Interstitial brachytherapy; Radiotherapy.