Order of operations

One of the most frequent questions I get asked is about my treatment plan, and why chemo is happening before radiation instead of the other way around. Until it was posed to me, I hadn’t thought to even ask about the order. It turns out, practical, evidence-based reasons apply, though it still surprises me how new some treatment recommendations are. The order of operations really is tailored to individual circumstance.

In my case, my cancer is stage 3A, which puts me at high risk for recurrence, and in particular, distant metastasis. And with >50% myometrial invasion (the muscle layer of the uterus), my cancer already has a high rate of local (pelvic) recurrence. Not fun information, but helpful when planning treatment.

There are three common approaches to treatment for locally advanced endometrial cancer — radiation followed by chemotherapy, chemotherapy and then radiation, and what is known as a ‘sandwich approach’ where the chemo cycles are broken up and radiation is delivered in the middle of the plan.

On its own, chemotherapy improves overall survival, while radiation reduces the incidence of local recurrence. Individually, neither improve the rate of distant recurrence but the thinking is that combined, they make up for individual shortcomings. This is backed up by a 2023 study that reviewed available evidence from 15 retrospective studies plus one clinical trial and found that chemotherapy combined with radiation showed significantly lower risk of local recurrence, total recurrence, better overall survival, progression-free survival, and disease-free survival. A separate study has raised questions whether chemotherapy alone has similar benefits.

The order of treatment has been the subject of a lot of recent research. Historically, radiation was the first line of treatment for advanced endometrial cancer. Chemotherapy became a component of standard of care in 2018, when international studies like PORTEC-3 showed progression-free survival benefits. More recently, new immunotherapy drugs added to treatment protocols make things more complex by adding options.

If I follow the data correctly, chemotherapy first mitigates the risk of distant recurrence by attacking any cancer cells that may be circulating but not yet visible on a scan. It does this by delivering drugs systemically — thoughout the body. And doing this first offers patients the best option of completing the chemotherapy cycles with the least side effects. Delaying radiation (as its described since radiation was formerly the first line of treatment) does not impact the rate of local recurrence in this scenario.

Nonetheless, there are windows of time and schedules where this data is valid, so timeline is equally as important as sequence. I’m holding out hope that the ‘break’ between chemo and radiation — which is really time for my body to heal and the radiation oncology team to do their assessments and refine my treatment plan — will be enough of a window for me to train and race a 10k in late September.

It’s all enough for me to craft a long list of questions for my radiation oncologist when we meet in August once I’ve completed chemotherapy. I know the current plan is five weeks of external radiation delivered five days a week (or 25 fractions as it’s described), along with three brachytherapy treatments, and I understand the role of each. This treatment is based on the characteristics of my cancer — the depth of myometrial invasion, and although it is an endometrioid adenocarcinoma, it has both squamous and clear cell characteristics. What I don’t yet understand is how we evaluate this dosage and, moreover, how we measure success.

Til then, I’m focused on navigating the constraints of chemotherapy while still enjoying the summer. This last week I struggled with energy levels. My resting heart rate was 8-10 points higher than normal and I found myself needing more sleep. I don’t know if it was the cumulative effects of chemotherapy so far or if the record-breaking temperatures outside played a role. Likely it was both. Either way, the net result was less working out. I chose to spend my ‘spoons’ — the energy I did have — on connecting with friends for a virtual happy hour and seeing Sarah McLachlan perform live for the first time in many years.

Fortunately, by Saturday morning, with a good night’s sleep and a break in the weather, I woke up feeling more like myself and my Garmin data reflected this. While I haven’t run this weekend, I have worked out twice, both at a walk pace to maximize time on feet versus testing paces.

So I’m optimistic for the week ahead. The third week of each chemo cycle has been the most ‘normal’ to date, and I’ve been bookmarking podcasts to listen to while I work out. With the US Olympic Track & Field trials underway, and the Canadian trials set to start, there’s lots of running news to keep my attention.