Alberta Cancer Foundation

Staying On Target

By: Colleen Seto

Dr. Geetha Menon. Photograph courtesy of John Ulan.

Over the past few decades, the incidence and mortality rate of cervical cancer has declined, largely because of screening. Caught early, the survival rate for cervical cancer is high.

However, “not all patients get diagnosed early, and surgery may not be possible,” says Dr. Geetha Menon, a medical physicist at Edmonton’s Cross Cancer Institute. In fact, cervical cancer is the fourth most common reproductive cancer in Canadian women. “For locally advanced cases of cervical cancer [where the tumour within the cervix is considered large or the cancer has grown into the tissue around the cervix], outcomes are not great.”

This is where Menon’s research on gynecological carcinomas and brachytherapy is making a real difference. When not amenable to surgery, curative-intent treatment of locally advanced cervical cancer involves a multimodality approach that includes a combination of external beam radiotherapy with concurrent chemotherapy, followed by a brachytherapy boost. Brachytherapy refers to a type of internal radiation therapy where a radioactive source is fed into an applicator that is placed inside the body, in or near the tumour, to deliver highly localized radiation treatment. This radiation boost is more effective at destroying cancer cells while minimizing damage to surrounding tissue.

“At the Cross, we treat about 40 to 50 cervical cancer patients with brachytherapy each year,” Menon says. “Learning from our years of experience and a large database of treatment information, the brachytherapy team at the Cross is continually performing innovative research aimed at providing better and more personalized brachytherapy treatments for women with cervical cancer.”

In concert with external beam radiation therapy, targeting tumours with high-dose radiation through MRI-based brachytherapy has significantly improved outcomes. “It’s shown to be essential for these patients,” says Menon. “It’s the gold-standard treatment for locally advanced cervical cancer cases.”

Specifically, as part of a leading worldwide collaboration, Menon and her team examined the anticipated treatment planning improvements of using MRI for brachytherapy, since the Cross is one of the first centres in Canada to use this technique.

“With a CT scan, it’s very difficult to differentiate the tissues in the pelvis,” she explains. “With its superior ability to visualize tissue, an MRI is not only the best imaging modality for tumour delineation, which is a crucial step when generating the radiation treatment plan,  but it also helps in making sure that the radiation dose to the nearby critical structures, like the rectum and bladder, is reduced.”

Dr. Geetha Menon at her lab in Edmonton. Photograph courtesy of John Ulan.

Cervical cancer brachytherapy applicators, used to guide the radiation sources, come in various shapes and sizes. “When an applicator is inserted into the uterus, it changes the anatomy significantly,” Menon explains. Prior to the brachytherapy procedure, doctors used MRIs taken without the applicator to make an educated guess to predict this change and to choose the suitable applicator for treatment. However, such speculations are quite challenging, as each patient’s anatomy is unique.

Menon is involved with a study where an artificial intelligence model was developed using MRI images taken before and after the brachytherapy procedure to predict how the uterus changes after an applicator is inserted. “This information will assist the doctors in efficient decision-making prior to the procedure, which, in turn, will make treatments better, faster and, most importantly, further improve outcomes.” She also points to the potential of using 3D printers to print custom applicators for personalized treatment.

Menon alluded to a current effort in North America to train more doctors in brachytherapy.

“It’s an advanced practice, and not every centre offers it,” she says. That means not all residents get exposure to training, resulting in fewer doctors with the expertise and surgical experience needed to perform brachytherapy. Fewer doctors and centres with this expertise means limited access to the treatment.

Menon is part of a team involved in the development of a virtual-reality simulation tool that takes the user through the brachytherapy process, from the initial preparatory step to performing procedures.

“It’s not just about the research,” says Menon. “I believe such efforts to encourage and train the next generation will produce competent trainees delivering superior brachytherapy treatments, resulting in improved treatment outcomes.”