Background: Both drug choice and delivered dose of intended treatment potentially influence outcome in patients treated for follicular lymphoma (FL). Historically, observational studies have solely evaluated drug choice. The National LymphoCare Study (NLCS) is a prospective, observational study that enrolled >2700 patients with FL in the United States between 2004 and 2007. We report on measures of delivered dose and its impact on outcomes for the most common first-line regimens.
Methods: All evaluable patients treated with R-CHOP, R-CVP, or R-fludarabine (R-Flu)–containing regimens in the NLCS were included, except those with FL plus other lymphoma histology, non-FL histology, or those who progressed before first treatment or before being assigned to watchful waiting. Associations between baseline factors and choice of treatment (R-CHOP, R-CVP, or R- Flu–containing regimen), number of cycles received (≤4, 5–6, 7+), and completion of therapy were assessed using the Pearson chi-square test. Factors associated with risk of early discontinuation were assessed using logistic regression, and a generalized logits model was used to assess the relationship between baseline factors and number of cycles received. Kaplan-Meier methods and the log-rank test were used to estimate progression-free survival (PFS), overall survival (OS), and time to next treatment.
Results: Among 1165 evaluable patients, a total of 648 received R-CHOP, 296 received R-CVP, and 221 received R-Flu combinations. Patient characteristics were similar between groups with the following exceptions: patients receiving R-CHOP were more likely to have grade 3 FL (38% vs 11% for R-CVP and 13% for R-Flu), and patients receiving R-CVP were older (25% ≥75 vs 8% for R-CHOP and 13% for R-Flu) and had higher Follicular Lymphoma International Prognostic Index (FLIPI) risk scores (50% poor FLIPI vs 41% for R-CHOP and 36% for R-Flu). The distribution of delivered cycles demonstrated a high degree of compliance with published regimens, with most patients receiving ≥5 cycles of treatment (R-CHOP 86%, R-CVP 81%, R- Flu 67%, P<.0001). The median cycle length was 21 days for both R-CHOP and R-CVP, and 29 days for the R-Flu regimens. Cycle intensity, defined as the expected cycle length (21 days for R-CHOP and R-CVP, and 28 days for R-Flu) divided by the actual cycle length, was between 0.9 and 1.1 for 68% of R-CHOP patients, 75% of R-CVP patients, and 45% of R-Flu patients. The percentage of patients with longer-than-expected time between cycles (cycle intensity <0.9) was similar for the 3 treatment groups; however, R-Flu patients were more likely to have shorter-than-expected time between cycles (24% vs 4% for R-CHOP and 3% for R-CVP). We sought to understand the reasons for patients receiving ≤4 cycles. Most patients who received ≤4 cycles were considered to have completed the intended duration of therapy (58% for R-CHOP, 62% R-CVP, and 75% R-Flu); rates of early discontinuation from the intended treatment were significantly less for patients receiving ≥5 cycles. Early discontinuation was associated with age ≥75 years and treatment with R-Flu (particularly in patients with grade 1–2 FL). Toxicity was the most commonly cited reason for early discontinuation (47% for R-CHOP, 46% for R-CVP, and 71% for R-Flu). The higher rate of R-Flu discontinuation due to toxicity is consistent with findings from other studies. Disease progression was rarely cited as the reason for early discontinuation. Time to retreatment was significantly shorter for patients receiving ≤4 cycles for patients receiving R-CHOP and R-CVP compared with patients receiving 5–6 cycles and 7+ cycles (P=.002 and P<.001 respectively; medians not yet reached). Delivery of ≤4 treatment cycles was associated with lower response rates (76% CR/PR vs 90% for 5–6 cycles and 92% for 7+ cycles) and worse PFS and OS, among patients who received R-CVP (all P<.01) but not among other regimens.
Conclusions: Most patients with FL receiving chemoimmunotherapy in the NLCS completed ≥5 cycles of treatment. Most who received fewer cycles were considered to have completed therapy, and therapy commonly was given at or above the expected cycle intensity. Strategies to improve dose delivery appear unlikely to impact patient outcomes, except possibly in patients receiving R-CVP.
