Brachytherapy is an important component in management of cervical cancer, enabling dose escalation with reasonable limitation of toxicity. However, in some patients, there is an inadvertent increase in OAR (Organs at Risk) doses. In our study, we analyse the dosimetric differences between the two commonly used ICBT (Intracavitary Brachytherapy) applicators in our hospital.
We performed a retrospective analysis of intracavitary brachytherapy (ICBT) plans using clinical records of 109 cervix cancer patients from Aug-2020 to Aug-2021. Patients who completed the ICBT course with the same applicators were chosen. 3 month follow up and symptom data was acquired from clinical records. The mean doses per patient were compared between FSD (Fletcher Suit Delclos) and Ring-Tandem applicator with ring cap.
Ring and Tandem applicator was used in 67 patients while the Fletcher Suit Delclos applicator was used in 42 patients. The mean bladder D2cc (Highest irradiated 2cc area), rectum D2cc were 79.2% vs 79.2% and 50.4% vs 63.2%. (σ = 19.4) The mean (Posterior Inferior Border of Pubic Symphysis) PIBS +2 and PIBS dose was 146% vs 218.5% and 49% vs 83.6%. At the time of 3 months of follow up, incidence of Grade 2 dysuria was compared (0.5% v 19.5%, p<0.05) Analysing the anatomical parameters, the AP pelvic diameter correlated negatively with the average D2cc of OARs. The rectum volume correlated positively with D2cc rectum (ρ, correlation coefficient = 0.44). The rectum (ρ = 0.01) and bladder diameter (ρ = 0.15) at the level of the flange also correlated positively with OAR D2cc.
It can be inferred from the study that the ring and tandem has a comparably favorable dosimetric profile and it should be evaluated further, with a view to decrease OAR toxicities and improve symptom free quality of life. The dose at PIBS should also be looked into further as a marker of vaginal toxicity and urethral toxicity, and brachytherapy dose delivery should be optimised accordingly.
The authors.
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All authors have declared no conflicts of interest.