PRIMARY HEPATIC LYMPHOMA: ROLE OF LOW‐DOSE RADIOTHERAPY AND PAIRED LITERATURE REVIEW

Abstract

Introduction: Primary hepatic lymphomas (PHL) are a rare form of non-Hodgkin lymphoma for which there are no established treatment guidelines. Available literature is largely comprised of small case reports and there are no reports on low-dose radiotherapy (RT) for indolent PHL. We report our institutional experience treating PHL within the context of existing literature to better understand the role of RT. We hypothesize that low-dose RT offers comparable outcomes to observation (obs), surgery and systemic therapy (ST) in select patients. Methods: We conducted a single-institution retrospective analysis of all biopsy-proven PHL patients (pts) diagnosed from 2000-2021 without other lymphomatous solid organ involvement. Subgroup analysis was performed for diffuse large B-cell lymphoma (DLBCL) and indolent lymphoma (IL). Univariable (UVA) and multivariable analysis (MVA) for overall survival (OS) was performed using the Cox proportional hazards model. Literature review was conducted using key words including “liver”, “lymphoma”, and “treatment” to identify all available reported cases of PHL. Results: We identified 30 PHL pts within our institution and 192 pts from literature review, with subgroup analysis of DLBCL and IL pts in the institutional cohort (n = 15, 9) and literature review (n = 78, 76), respectively (Table 1). Among the IL institutional cohort (n = 9), 3 pts underwent obs and 2 each received RT, ST and surgery. There were no recurrences among pts treated with RT, surgery or obs with median OS of 12.4 years, whereas both ST pts experienced either transformation to DLBCL or recurrence. Both RT patients received low-dose RT of 4Gy in 2 fractions. Literature review identified only 1 case report of RT use for IL with a dose of 41.4Gy. Conclusions: There is limited literature regarding use of RT in indolent PHLs. We present the first report of low-dose RT for indolent PHL with comparable outcomes to alternative modalities. PHL DLBCL is predominantly treated with ST in both our institutional experience and in the literature. Although our data is limited by the small cohort size reflective of the rarity of disease, our results are encouraging for the consideration of low-dose RT as a management option for appropriate patients with indolent PHL. Keywords: extranodal non-Hodgkin lymphoma, radiation therapy No conflicts of interests pertinent to the abstract.