Hematologic recovery after central lymphatic irradiation for patients with stage I-III follicular lymphoma.

BACKGROUND The authors previously reported that central lymphatic irradiation (CLI) can induce molecular remission in patients with Stage I–III follicular lymphoma, as measured by polymerase chain reaction analysis for t(14;18) (q32;q21). Hematologic toxicity has been considered a major consequence of CLI. This study was undertaken to analyze the patterns of hematologic recovery after CLI. METHODS Thirty-three patients with Stage I–III follicular lymphoma were treated with CLI between January 1993 and February 1998. CLI consisted of irradiation to mantle, upper two-thirds of abdomen, and pelvic fields. Each field was treated to 30.0–30.6 grays (Gy) at 1.5–1.8 Gy per fraction, with a boost to 36.0–39.6 Gy at the same rate to the sites of macroscopic disease. A break of approximately 4 weeks was given after treatment of each field. Twenty-four patients who were followed for a minimum of 1 year from the end of CLI form the basis of this analysis. Fourteen patients were male. Three patients had Stage I disease, 6 patients had Stage II disease, and 15 patients had Stage III disease. The International Prognostic Index (IPI) for malignant lymphoma was 0 for 5 patients, 1 for 13 patients, and 2 for 6 patients. The Eastern Cooperative Oncology Group performance status was 0 for 21 patients and 1 for 3 patients. The median values for their pretreatment characteristics were as follows: age, 60 years (range, 34–73 years); height, 173 cm (range, 155–193 cm); weight, 79 kg (range, 57–107 kg); body surface area (BSA), 1.95 m2 (range, 1.61–2.31 m2); bone marrow cellularity, 27%(range, 2–75%), platelet count, 233,000/mm3 (range, 139,000–339,000/mm3), white blood cell (WBC) counts, 6400/mm3 (range, 4200–10,900/mm3); and hemoglobin, 14.5 mg/dL (range, 11.8 –16.6 mg/dL). The median duration of CLI was 159 days (range, 137–345 days). Ten patients had cardiovascular disease. The number of sites receiving a boost dose of ≥ 36.0 Gy was 0 sites in 1 patient, 1 site in 6 patients, 2 sites in 11 patients, 3 sites in 5 patients, and 4 sites in 1 patient. The platelet, hemoglobin, and WBC counts were followed every 3 months after completion of CLI. These counts were normalized to the pretreatment counts for statistical analyses. Univariate and multivariate analyses were performed to investigate the correlations between patient factors and hematologic status at 1 year posttreatment. Pearson correlation analysis was used for the continuous factors (patient age, height, weight, BSA, bone marrow cellularity, and duration of CLI), and the Mann–Whitney test was used for categoric factors (IPI, gender, performance status, stage, number of sites receiving ≥ 36.0 Gy, and presence or absence of cardiovascular disease). RESULTS There was continued recovery, essentially approaching the pretreatment levels, over 3 years for platelet, WBC, and hemoglobin counts. Factors that were associated significantly with normalized platelet counts at 1 year by univariate analyses were age (P = 0.015) and cardiovascular disease (P = 0.041). Age was the only significant factor by multivariate analyses, with older patients having lower platelet counts at 1 year posttreatment. No factors were found that were associated significantly with 1-year normalized WBC or hemoglobin levels by either univariate or multivariate analyses. CONCLUSIONS All three of the hematologic components (platelets, WBC, and hemoglobin) essentially recover after patients undergo CLI over a 3-year period. Older age was the only significant adverse factor that affected the platelet recovery, as detected by multivariate analysis. Cancer 2001;92:1074–9. © 2001 American Cancer Society.