Bulky tumours in PCNSL tied to high local treatment failure

Systemic and intrathecal therapies are necessary for local control in patients with primary central nervous system lymphoma (PCNSL), but bulky tumours remain a problem, according to a study.

Ninety-five consecutive patients with pathologically confirmed PCNSL were included in this retrospective review from 2002 to 2021. Of these, 29 had progressive disease.

The investigators used Kaplan-Meier method, log-rank test, and Cox proportional hazard models to explore the associations of patient, tumour, and treatment variables with local control (LC), progression-free survival (PFS), and patterns of first failure.

Majority of the patients (62 percent) were aged <65 years and had Karnofsky Performance Status (KPS) >70 (64 percent) and negative cerebrospinal fluid (CSF) cytology (70 percent). The median tumour volume in 70 patients with MRI scans was 12.6 mL.

One-year PFS was 48 percent and 1-year LC was 80 percent over a median follow-up of 11 months. Twenty-nine patients had disease progression, of whom 24 percent were distant only, 17 percent distant and local, and 59 percent local only.

Multivariate analysis revealed the association of LC with age (hazard ratio [HR], 1.08/y; p=0.02), KPS (HR, 0.10; p=0.02), completion of >6 cycles of HD-MTX (HR, 0.10; p<0.01), and use of intrathecal chemotherapy (HR, 0.03; p<0.01).

In univariate analysis, local only first failure was common in tumours >14 mL (odds ratio, 5.06; p=0.08), with 1-year LC of 83 percent in tumours <14 mL as opposed to 64 percent in tumours >14 mL.

No significant associations were seen with LC and whole brain radiotherapy (p=0.37), rituximab (p=0.12), or attempted gross total resection (p=0.72).

“Our findings reaffirm the importance of systemic and intrathecal therapies for local control in PCNSL,” the investigators said. “However, bulky tumours trend to fail locally, warranting further investigation about the role of local therapies or systemic therapy intensification.”