PracticeUpdate Oncology Best of 2018

CONFERENCE COVERAGE 34

High-Dose Radiotherapy Improves Survival Substantially in PatientsWith Oligometastatic Cancer Stereotactic ablative radiation therapy doubles PFS in patients with oligometastatic cancer. S tereotactic ablative radiotherapy has been shown to extend the lives of patients with oligometastatic cancer greatly, and to double their survival with- out cancer. Stereotactic ablative radiotherapy delivers substantially higher doses of radiation to the tumor site in one or a few treatment sessions. " …results from this

Of patients who received standard radi- ation, 9% experienced serious adverse events (grade ≥2). Of those in the stereo- tactic radiation arm, 30% experienced such events (P = .022) and 3 patients died of an adverse event. Dr. Palma noted that an experienced team must carefully deliver stereotactic radia- tion therapy because there is a small risk of serious side effects and mortality. He also suggested that the overall survival bene- fit outweighs these risks for patients with metastases who are not expected to live otherwise. The two treatment arms did not differ in measures of quality of life, however. Scores on the Functional Assessment of Cancer Therapy: General questionnaire 6 months after treatment were similarly high for both patient groups. Patients reported similarly high outcomes on the physical, social, functional, and emotional subscales of the same questionnaire. Some patients developed additional lesions during the trial that in some cases were ablated successfully. More sites were treated successfully than not in these patients. A follow-up study will enroll patients with up to 10 metastatic lesions, SABR-COMET-10. According to Dr. Palma, the limit of how many tumors can be treated using ste- reotactic radiation is unknown. The main concern is determining safe boundaries for the amount of radiation exposure patients can tolerate. Because this is a new tech- nology, he noted that treatment has been very conservative. Overall, 46% of patients treated with ste- reotactic radiation were alive after 5 years to an increased survival of a median of 13 months. This survival benefit was surprising in patients with metastatic disease. " randomized trial show for the first time that high-dose radiation effectively treats limited recurrences, leading

Dr. Palma and colleagues enrolled 99 patients whose cancer had returned in as many as five locations, though in most (n=92), cancer had spread to one to three new sites. Between 2012 and 2016, patients with a median age of 68 (range 43–89) years were randomized 1:2 to palliative standard of care or standard of care + stereotactic radiation to all metastatic lesions and were followed for a median of 27 months. Most suffered from cancer of the breast (n=18), lung (n=18), colon or rectum (n=18), and prostate (n=16). Patients who received stereotactic ablative radiotherapy experienced a median over- all survival of 41 (95% CI 26, upper limit not reached) months versus 28 (95% CI 19–33) months in the standard radiation arm (P = .09). Stereotactic radiation also doubled survival without cancer growth. Progression-free survival was 12 (95% CI 6.9–30) months in the stereotactic arm versus 6 (95% CI 3.4– 7.1) months for those who received standard radiation (P = .001). Stereotactic radiation resulted in more neg- ative side effects (most commonly fatigue (n=10), dyspnea (n=9), muscle and joint pain (n=7), bone pain (n=6), or pain not otherwise specified (n=7) than standard radiation.

These findings of the randomized, phase II, open-label, multicenter Stereotactic ABla- tive Radiotherapy for the Comprehensive treatment of OligoMEtastatic Tumors (SABR- COMET) trial was reported at ASTRO 2018. David Palma, MD, PhD, of the London Health Sciences Centre in Ontario, Canada, noted that traditionally, patients have been considered to be incurable when cancer spreads to other parts of the body. How- ever, the oligometastatic theory suggests that patients with only a few recurrent can- cerous spots may be treated with surgery or radiation, leading to improved survival. Dr. Palma noted that results from this ran- domized trial show for the first time that high-dose radiation effectively treats lim- ited recurrences, leading to an increased survival of a median of 13 months. This sur- vival benefit was surprising in patients with metastatic disease. According to Dr. Palma, each oncologist must decide whether to offer this treatment as the standard of care for patients with oligometastases, but he suggests that this treatment option should be considered. He also emphasized that stereotactic radiation increased overall and progression-free sur- vival with no detrimental impact on patient quality of life.

vs 24% in the control group. www.practiceupdate.com/c/74921

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