In a UK observational cohort study reported in the Journal of Clinical Oncology, Price et al found that pretreatment absolute lymphocyte count (ALC) was associated with overall survival and predictive of benefit of the addition of cisplatin to radiotherapy in patients with oropharyngeal squamous cell carcinoma.
As stated by the investigators, “There is a need to refine the selection of patients with oropharyngeal squamous cell carcinoma for treatment de-escalation. We investigated whether pretreatment ALC predicted overall survival benefit from the addition of concurrent chemotherapy to radical radiotherapy.”
Study Details
The study included data from a cohort of 791 consecutive patients with oropharyngeal squamous cell carcinoma treated by curative-intent radiotherapy with or without concurrent chemotherapy at The Christie NHS Foundation Trust between 2011 and 2018 and a validation cohort of 609 patients treated at The Leeds Teaching Hospitals NHS Trust between 2013 and 2020. The primary endpoint was overall survival at 5 years.
Key Findings
On multivariate analysis in the discovery cohort, log increases in baseline ALC were significantly associated with improved 5-year overall survival (hazard ratio [HR] = 0.64, 95% confidence interval [CI] = 0.42–0.98, P = .039).
Baseline ALC was predictive of benefit of use of concurrent cisplatin chemotherapy, with a significant interaction found between cisplatin treatment and ALC (likelihood ratio test P = .04): higher ALC in patients who received cisplatin reduced the 5-year survival benefit compared with radiotherapy alone (HR = 2.53, 95% CI = 1.03–6.19, P = .043). Thus, patients with high ALC did not benefit from the addition of cisplatin. In contrast, patients with low ALC had poorer prognosis with radiotherapy alone that was improved with the addition of cisplatin; the lower the pretreatment ALC, the larger the potential benefit of cisplatin.
The overall survival benefit of higher ALC appeared to be driven by a beneficial effect on locoregional control up to 5 years (interaction subdistribution HR = 2.29, 95% CI = 0.68–7.71, P = .094).
Findings in the validation cohort were similar for the association of ALC with overall survival, showing that higher ALC in patients who received cisplatin reduced the 5-year survival benefit compared with radiotherapy alone (HR = 2.53, 95% CI = 0.98–6.52, P = .055), and indicated that the survival benefit with higher ALC was driven by locoregional control (interaction subdistribution HR = 3.43, 95% CI = 1.23–9.52, P = .018).
The investigators concluded: “For [oropharyngeal squamous cell carcinoma], the pretreatment ALC is prognostic for [overall survival] and also predicts benefit from the addition of cisplatin chemotherapy to radiotherapy. These findings require prospective evaluation, and could inform the selection of good prognosis patients for a de-escalation trial.”
David J. Thomson, MD, of The Christie NHS Foundation Trust, Manchester, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by NIHR Manchester Biomedical Research Centre, Cancer Research UK, and others. For full disclosures of the study authors, visit ascopubs.org.
