This is one of the questions I am most frequently asked by patients with cervical cancer, and I want to answer it directly because I am aware that brachytherapy, which involves placing a radiation applicator inside the vagina and cervix under short anaesthesia, is an aspect of treatment that some patients find alarming and are sometimes advised they can forgo. They cannot, if the intent of their treatment is cure. The reason brachytherapy cannot be replaced by external beam radiation alone comes down to physics. The dose of radiation needed to kill the central tumour in a cervical cancer is very high, higher than can be delivered to the cervix from outside the body without also delivering an unacceptably high dose to the bladder, which sits immediately in front of the cervix, and the rectum, which sits immediately behind it. The radiation dose from an external beam falls off with distance, but not steeply enough at the short distances involved in pelvic anatomy to protect the bladder and rectum while maintaining a tumoricidal dose at the cervix. An internally placed source, positioned directly at the tumour or within the applicator at the cervix, delivers its dose with a very steep fall-off: the tumour receives a very high dose, while the bladder and rectum, just two or three centimetres away, receive a dose that is a fraction of the tumour dose. This physics cannot be replicated from outside the body. My research in brachytherapy, recognised with the Best Paper Award from the Indian Brachytherapy Society in 2016, reflects my long engagement with the technical and clinical dimensions of brachytherapy delivery. At SPARSH Hospital, Hennur Road, Bengaluru, brachytherapy is performed as a standard part of curative-intent cervical cancer treatment, and I discuss the procedure, the anaesthesia, and what to expect in detail with every patient before the brachytherapy sessions begin.
Written by Dr. P Sasikala, MBBS, DMRT, DNB (Radiation Oncology), Best Paper Award (Indian Brachytherapy Society, 2016), Karnataka Leadership Award, Consultant Radiation Oncologist, SPARSH Hospital, Hennur Road, HBR Layout, Bengaluru 560043. Monday to Saturday, 9:00 AM to 5:00 PM. Phone: +91 80958 09322.
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