Predicting Recurrence in Rectal Cancer Watchful Waiting
TOPLINE:
The Immunoscore biopsy, which quantifies immune cell tumor infiltration in tumor biopsies at baseline, is a strong predictor for rectal cancer recurrence for both local regrowth and distant metastasis during watchful waiting.
METHODOLOGY:
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Currently, oncologists do not have a biomarker that can help select patients with rectal cancer for watchful waiting after neoadjuvant chemoradiotherapy as well as help monitor them over time. And about 25% of patients on watchful waiting will eventually relapse.
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The Immunoscore biopsy quantifies the degree of immune infiltration on pretreatment tumor biopsies, looking at the density of CD3- and CD8-positive T cells at baseline, given that greater infiltration has been associated with prolonged treatment response.
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To determine whether the Immunoscore can help select patients for watchful waiting, investigators correlated Immunoscore with time to recurrence in 249 patients with stage I-III rectal cancer who were undergoing watchful waiting after complete clinical responses to neoadjuvant chemoradiotherapy.
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CD3- and CD8-positive T-cell densities were converted into percentiles and then translated into scores of Immunoscore biopsy: low (0%-25%), intermediate (> 25%-70%), and high (> 70%-100%).
TAKEAWAY:
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The Immunoscore biopsy significantly improved predictions of recurrence: 5-year recurrence-free survival was 91.3% among patients with high scores, 62.5% among those with intermediate scores, and 53.1% among those with low scores.
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The Immunoscore was significantly associated with disease-free survival (log-rank P = .0002) and predicted both local regrowth and distant metastasis.
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On multivariate analysis, the Immunoscore’s predictive ability was independent of age, sex, tumor location, cT stage, and cN stage, and was the strongest predictor of time to recurrence (hazard ratio, high vs low, 6.93; P = .0017).
IN PRACTICE:
This validation study confirms that the Immunoscore biopsy “is an independent parameter predicting time to recurrence” and can help physicians and patients decide whether to opt for watchful waiting, the study authors write.
SOURCE:
The study, led by Carine El Sissy of the Laboratory of Integrative Cancer Immunology, Paris, was published on October 3 in the Journal of Clinical Oncology.
LIMITATIONS:
Mismatch repair gene expression status was not assessed.
DISCLOSURES:
The work was supported by the L’Institut National de la Santé et de la Recherche Médicale and others. Investigators disclosed patents related to the work and ties to many companies, including Amgen, AstraZeneca, and Merck. One investigator is an employee of Novo Nordisk, and another is employed by Veracyte.
M. Alexander Otto is a physician assistant with a master’s degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape. Alex is also an MIT Knight Science Journalism fellow. Email: [email protected]
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