The Impact of First Complete Remission by PET-CT and Time to Next Treatment on Survival of Follicular Lymphoma Patients.

We retrospectively analyzed the impact of initial positron emission tomography and computed tomography (PET-CT) complete remission (CR) and time to next treatment (TTNT) on patient outcome in follicular lymphoma. Between 2002 and 2014, 150 patients could be evaluated for treatment response and long-term outcome. The CR after first line treatment with either rituximab-cyclophosphamide, oncovin, and prednisolone (R-COP) or rituximab-cyclophosphamide, doxorubicin, oncovin, and prednisolone (R-CHOP) was 89% and partial response (PR) was 7%. The 5- and 10-year survival rates were 86.0% and 62.6%, respectively. In five years, 11% of patients had died of lymphoma and 3% from other causes. Forty-seven patients (31%) underwent a second line of treatment comprising 19 (40%) with a TTNT shorter than 24 months and 28 (60%) longer than 24 months. There was no difference in overall survival (OS) between R-COP (86%) and R-CHOP (77%) at 5 years, but there were more next treatment events in the R-COP compared with the R-CHOP group on longer follow-up (60% versus 35% at 8 years). For PET-CT response, there was a significant OS difference between initial CR and PR patients (88% versus 70%, p < 0.01), and a longer TTNT was seen in initial CR patients. Patients with a TTNT longer than 24 months had better OS compared with patients with a shorter TTNT (93% versus 54% at 5 years, p < 0.01). In conclusion, patients with initial PET-CT CR and TTNT longer than 24 months had better OS compared with those achieving only PR and shorter TTNT. PET-CT CR should be considered the treatment goal during initial treatment, and more aggressive treatment should be considered for patients with a TTNT of less than 24 months.