Splenic marginal zone lymphoma (SMZL) is a rare, indolent non-Hodgkin’s lymphoma that commonly involves the spleen, bone marrow, and blood. This letter describes a 78-year-old woman with long-standing SMZL presenting with a rare case of breast involvement. Treatment options are not well researched in older adults who have limited life expectancy because of multiple comorbidities. The complex decision-making process included exploring the woman’s life circumstances and behaviors. The only therapeutic option available was radiation therapy, which would not reduce mortality but might reduce disease-specific morbidity. Quality of life may be compromised because of side effects from radiation therapy. This case describes additional challenges of decision-making in the context of cognitive impairment.