Dear Editor,
I have read with great interest one of the recent articles entitled “Efficacy of medial needles in mitigating dose deficits from sub-optimally inserted tandems in cervical interstitial brachytherapy” [1]. The authors have highlighted and offered a simple, yet practical solution to a common issue faced during routine brachytherapy applications, which needed to be addressed. While it is crucial to ensure optimal insertion of the tandem and ovoids, inappropriate tandem insertion is not uncommon. The incidence of sub-optimal insertions is 6.0-7.5% despite the availability of image guidance [2, 3]. These are not limited to misplaced tandems, but also include uterine wall or fundus perforation.
Multiple factors can lead to inadequate tandem insertion with major factors being age, cervical adhesions, myometrium invasion of a tumor, and uterine retroversion [4]. Also, inexperienced hands are a risk factor, as applicator insertion is associated with a steep learning curve. Few solutions (with their limitations) to mitigate improper tandem insertion in some of these circumstances may include:
Iatrogenic cervical dilation under spinal or general anesthesia – resource-intensive;
Real-time ultrasonography – not useful in case of fibrosis and/or obstruction by tumor itself;
Laparoscopy-assisted tandem insertion – limited expertise and invasive procedure.
It is relevant to mention that one of the previously published studies had reported that the mid ventral needles are not essential in treatment planning unless situated in the vicinity of residual grass tumor volume (GTV) [5]. However, it appears now that they are not so “non-essential” per se, as they come handy in situations where tandem is not optimally inserted, helping in mitigating dose deficits near high-risk volumes without compromising dose to organs at risk (OARs), as indicated in the current study.
Future research on this topic should explore drawbacks associated with medial needles, e.g., potentially increased dose to nearby OARs as well as to explore and compare with other alternatives to improve dosimetry, such as deep insertion of lateral needle (potential for organ perforation) and increased activation of lateral needles (potential for increased dose to OARs).
While there can be no single best solution for each patient considering variable anatomy, nature of problem, and expertise available, such studies will indeed provide physicians with a choice, offering the opportunity to make informed decisions in the best interest of individual patients.
