Using a non-invasive treatment option of radiotherapy may be a better approach for certain patients, especially because it involves “no scalpels or anesthetics,” an expert said.
Patients with inoperable kidney cancer experienced 100% local control (no progression of their primary renal cell cancer) and cancer-specific survival when treated with stereotactic ablative body radiotherapy (SABR), according to the results of a recent trial.
Trial findings, published in The Lancet Oncology, showed that, “given the absence of other potentially curative options for inoperable patients with larger tumors or a location not amenable to thermal ablation, SABR can be considered a proven modality,” researchers wrote.
“There is a new, non-invasive option for cure for patients with primary kidney cancer – SABR as a treatment is now established with high-quality clinical trial evidence,” said study co-author Shankar Siva, a professor in the department of radiation oncology, Peter MacCallum Cancer Centre in Melbourne, Australia.
Speaking via email, Siva explained the procedure to CURE®.
“SABR is a non-invasive treatment involving focused beams of radiation used to sterilize the kidney cancer,” he said. “It can be delivered in as little as one to three outpatient day visits and involves no scalpels or anesthetics. It is an appropriate option for those patients who are at high risk of dialysis post-surgery or have other medical issues that might make surgery risky. Importantly, SABR is effective for both smaller and larger primary kidney cancers.”
The current standard of care for patients with primary renal cell carcinoma is surgery, which involves the removal of the entire kidney or surrounding tissues or the tumor plus a margin — but older patients may have medical comorbidities that may exclude them from surgery, according to the study. Researchers noted that percutaneous thermal ablation, which uses heat to destroy a tumor, has been proposed as an alternative to surgery, but “has several technical limitations and there is an absence of published clinical trial evidence to support its use.”
“In essence,” Siva said, “the majority of this group of patients really did not have a suitable curative treatment alternative in this study.”
“We have patients who probably need their kidney tumor treated, but they have some comorbidities — maybe they’re older, they really don’t want to go through surgery — so there’s that population who would like to get rid of their kidney tumor, but really don’t want to go [through surgery],” noted Susan Poteat, medical science liaison for the Kidney Cancer Coalition. “Nephrectomy, whether it’s robotic or open, it’s a pretty major surgery. So for those patients who either can’t or don’t want to go through a major surgery, it’s nice to have a non-invasive option. And it looks like from the results of this [study], for some patients, it’s a non-inferior option.”
Seventy patients (median age 77, 70% male) enrolled in the study and initiated treatment between July 28, 2016 and Feb. 27, 2020. Eligible patients were adults with primary renal cell cancer with one lesion who were medically inoperable, were at high risk of complications from surgery or had declined surgery and had an ECOG performance status of 0 to 2, meaning patients were capable of self-care but potentially limited in their abilities to perform work tasks.
The 12-month local control rate was 100%, and at a median follow-up of 43 months, researchers reported that there were no local failures observed during the trial. Cancer-specific survival was 100%.
Absence of distant failure (the time from the start of treatment until the first documented distant progression) at 12 and 36 months from the start of treatment was 97%, while overall survival (when a patient is still alive following treatment, regardless of disease status) was 99% at 12 months and 82% at 36 months from the start of treatment.
“Throughout the entire period of follow-up — which we had participants on follow-up beyond 5 years — there were no recurrences within the treated kidney in any of the patients,” Siva said.
Seven patients experienced one or more grade 3 treatment-related side effects, with grade 3 side effects that were designated as possibly, probably or definitely related to treatment, researchers reported, including nausea and vomiting (three patients), abdominal, flank or tumor pain (four patients), colonic obstruction (two patients) and diarrhea (one patient). Fifty-two patients experienced grade 1 to 2 treatment-related side effects and 11 patients did not report any treatment-related side effects.
“The side effects were limited,” Siva said. “One in ten patients had a side effect that was severe enough that require a short hospital stay. All patients requiring surgery would usually be admitted into the hospital for care for several days. Kidney function after SABR was comparable to surgery to part of the kidney and likely better than that of surgery to remove the whole kidney.”
Given their findings, the study authors also urged that the findings be considered for escalation to a trial comparing surgery to SABR as a primary treatment modality among operable patients.
Poteat, a medical physicist, said such a move would be appropriate.
“I did know that there were two patients [in the study] who had bowel obstruction,” she said. “The bowel is very sensitive to radiation, [it] can cause some scarring or even perforation, and one of the problems with most of our current radiation machines is they make a plan based on what the abdomen looks like the day it was planned, but bowel moves around, and so if you have a kidney cancer that’s lateral and on the outside, that may not be a problem but for some patients, there may be a somewhat higher risk of bowel perforation. They may want to change their selection a little bit, but I think many patients who had a low risk of those ongoing effects would choose this as an easier option than surgery.”
When in conversation with their care teams, Siva said, “Patients should be aware of their options.”
“They should ask their surgeon and multidisciplinary team whether SABR might be an appropriate option for them, particularly if surgery is on the riskier side for them,” she said.
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