Jillian Tsai
​Dr. Jillian Tsai, Lead of the Allen and Ruth Kerbel Palliative Radiotherapy and Oligometastasis Program (PROP) at Princess Margaret Cancer Centre, launched this clinical trial while working as a radiation oncologist at the Memorial Sloan Kettering Cancer Center in New York. The PROP team in the Princess Margaret's Radiation Medicine Program has a long history of providing rapid turnaround radiotherapy for patients with metastatic cancer. (Photo: UHN StRIDe Team)

A phase 2 clinical trial led by an investigator at Princess Margaret Cancer Centre and conducted at Memorial Sloan Kettering Cancer Center demonstrated the efficacy of stereotactic body radiotherapy (SBRT), a type of precision radiotherapy, in controlling resistance to drug therapy for non-small cell lung cancer (NSCLC).

NSCLC is the most common type of lung cancer, and it is usually diagnosed at an advanced stage, often when it has already spread to other parts of the body.

Standard treatments such as chemotherapy, targeted therapy, or immunotherapy often become less effective over time, leading to oligoprogressive disease, where cancer develops resistance and grows in certain areas. This leads to a need for alternative therapies.

"Our goal in this study was to evaluate whether SBRT can control cancer growth in specific areas, while allowing the drug treatment to continue working in the rest of the body," explains Dr. C. Jillian Tsai, Lead of the Allan and Ruth Kerbel  Palliative Radiotherapy and Oligometastasis Program (PROP) and Medical Director of the Princess Margaret Cancer Registry.

SBRT is a type of radiotherapy that utilizes advanced image guidance to deliver precise, intense doses of energy beams to cancer cells while minimizing damage to healthy tissue.

The research results from the CURB trial (Consolidative Use of Radiotherapy to Block Oligoprogression), published in The Lancet, demonstrated that SBRT could effectively stop cancer growth better than drug therapy alone.

Unlike conventional radiation, SBRT minimizes damage to healthy tissues, enabling higher treatment doses to target tumours effectively and minimize side effects, ultimately improving patient outcomes and overall health. (Graphic: Getty Images)

In the trial, which involved 106 patients with NSCLC, for those who received SBRT cancer growth was restricted for 10 months, compared to 2.2 months in the group receiving only standard drug therapy.

Despite the significant benefits observed in patients with lung cancer, no observable impact on patients with breast cancer was noted.

"The differences could be because patients with breast cancer who enrolled in the trial had undergone multiple lines of drug therapy, making the tumour more resistant," suggests Dr. Tsai. "It could also be because at the time of study enrollment, patients with breast cancer already had more 'hidden' widespread disease than what was detected on imaging, making local therapy less effective."

The findings emphasize that adding SBRT to the treatment plan for oligoprogressive NSCLC could significantly improve outcomes.

Looking ahead, Dr. Tsai, together with the Canadian Cancer Trials Group (CCTG), will be conducting a phase 3 trial in 2024 to validate these findings in a larger population of patients with lung cancer.

The CURB trial results, along with other research, underscore the advantages of involving radiation oncology early in the treatment of metastatic cancers. While historically focused on palliative care, the evolution of advanced, targeted, and higher-dosage radiotherapy techniques represents an opportunity to proactively prevent symptoms and potentially impede disease progression.

This work was supported by the National Cancer Institute, the Breast Cancer Research Foundation, and the National Institutes of Health.​

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