Given the indolent behavior of follicular lymphoma (FL), it is controversial whether limited stage FL can be cured using radiotherapy (RT). Furthermore, the optimal RT field size is unclear. The authors of this report investigated the long-term outcomes of patients with limited stage FL who received RT alone and studied the impact of reducing the RT field size from involved regional RT (IRRT) to involved node RT with margins up to 5 cm (INRT≤5 cm).
Eligible patients had limited stage, grade 1 through 3A FL diagnosed between 1986 and 2006 and treated were with curative-intent RT alone. IRRT encompassed the involved lymph node group plus ≥1 adjacent, uninvolved lymph node group(s). INRT≤5 cm covered the involved lymph node(s) with margins ≤5 cm.
In total, 237 patients were identified (median follow-up, 7.3 years) and included 48% men, 54% aged >60 years, stage IA disease in 76% of patients, elevated lactate dehydrogenase (LDH) in 7% of patients, grade 3A tumors in 12% of patients, and lymph node size ≥5 cm in 19% of patients. The 2 RT groups were IRRT (142 patients; 60%) and INRT≤5 cm (95 patients; 40%). At 10 years, the progression-free survival (PFS) rate was 49%, and the overall survival (OS) rate was 66%. Only 2 patients developed recurrent disease beyond 10 years. The most common pattern of first failure was a distant recurrence only, which developed in 38% of patients who received IRRT and in 32% of patients who received INRT≤5 cm. After INRT≤5 cm, 1% of patients had a regional-only recurrence. Significant risk factors for PFS were lymph nodes ≥5 cm (P = .008) and male gender (P = .042). Risk factors for OS were age >60 years (P < .001), elevated LDH (P = .007), lymph nodes ≥5 cm (P = .016), and grade 3A tumors (P = .036). RT field size did not have an impact on PFS or OS.
Disease recurrence after 10 years was uncommon in patients who had limited stage FL, suggesting that a cure is possible. Reducing RT fields to INRT≤5 cm did not compromise long-term outcomes. Cancer 2010. © 2010 American Cancer Society.