Serial radiation therapy is safe and effective as an alternative treatment to systemic therapy for kidney cancer

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In a new single-arm study, researchers at the MD Anderson Cancer Center at the University of Texas reported that monotherapy radiation therapy is a safe and effective non-invasive treatment for oligometastatic renal cell carcinoma (CRC). The results were published today in The Lancet Oncology.

Led by Chad Tang, MD, assistant professor of radiation oncology, the MD Anderson RCC Oligometastasis Phase II trial is the first study to investigate and report the use of stereotaxic body radiation therapy (SBRT) as an alternative treatment to standard systemic care . therapy for oligometastatic RCC, a medical condition in which a small number of new RCC tumors form in one or two other areas of the body. Serial SBRT monotherapy has demonstrated antitumor activity and achieved a median progression-free survival (PFS) of 22.7 months in patients with RCC, the most common type of kidney cancer.

“These findings are exciting because we challenge the dogma in radiation oncology that RCC is biologically resistant to radiation,” Tang said. “Our strategy of iterative irradiation of tumors as they grow and appear has shown promising results. This adds to a growing body of evidence suggesting / indicating that radiation therapy may offer an alternative treatment beyond systemic therapy for patients with this disease. “

SBRT uses highly concentrated doses of radiation to precisely treat tumor sites without damaging surrounding healthy tissue. Guided by computed tomography (CT), magnetic resonance imaging (MRI) and other advanced imaging techniques to map the position and shape of the tumor and determine its exact angles and intensities, SBRT is a local treatment non-invasive that can be applied repeatedly to control metastatic lesions in various anatomical locations. This approach is typically used to treat patients with early stage small lung cancer and prostate cancer.

For patients with kidney cancer, radiation therapy is more often used as a palliative approach to relieve pain or manage symptoms, while systemic therapies – such as immunotherapy and targeted agents – are typically used as treatments. frontline. Although very effective, systemic therapeutics affect the whole body and can be associated with significant toxicities.

“In developing this new radiation therapy strategy, we have sought to change the treatment paradigm with the goal of providing some patients with RCC with an alternative treatment that is less toxic and less toxic than systemic therapy,” said Tang.

From July 2018 to September 2020, researchers recruited 30 patients who were diagnosed with RCC of the clear cell subtype and who had five or fewer metastatic lesions. The trial included 20 Caucasian (67%), 7 Hispanic (23%), 2 black (7%), and 1 Native American (3%) participants. The median age was 65, with six women (20%) and 24 men (80%). The primary endpoints of the study were to estimate PFS and assess feasibility.

Overall, radiotherapy was well tolerated with conservative management. All patients completed at least one series of radiation therapy without requiring dose reduction or discontinuation due to toxicities. Six patients (20%) had a grade 2 or less adverse event, two patients had a grade 3 event (muscle pain and weakness), and one patient had a grade 4 event (hyperglycemia).

Biopsies collected three months after treatment confirmed that radiation therapy was effective in eliminating viable tumor cells or significantly reducing their proliferation. The researchers performed CT-guided biopsies on 14 patients at the first follow-up. Six patients (43%) tested negative for viable malignancy. All of the remaining patients the researchers were able to test showed a significant reduction in tumor cell proliferation, from 15% before radiation therapy to 6% after treatment. At the end of the reported study period, 23 patients (77%) had still not received systemic therapy.

While larger randomized trials will be needed to further investigate the risks and benefits of SBRT as monotherapy, the study showed that radiotherapy for the treatment of oligometastatic RCC is feasible and produced favorable results with minimal toxicity. .

“In view of these results, I am encouraged that serial radiation therapy for oligometastatic RCC has the potential to change practice,” said Tang. “We are offering patients another treatment option that minimizes the burden of toxicity on the body, while prolonging survival and maximizing their quality of life. We plan to continue studying this strategy on

patients with a slightly greater disease burden and to analyze the biomarkers of these treated patients in order to improve our ability to select patients who benefit from this treatment.

The trial was supported by the Anna Fuller Foundation, the Cancer Prevention and Research Institute of Texas (CPRIT), and the National Cancer Institute. Pavlos Msaouel, MD, Ph.D., assistant professor of genitourinary medical oncology, was co-first author and Nizar Tannir, MD, professor of genitourinary medical oncology, was principal author. A full list of co-authors and their disclosures can be found here.


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