Practices and Outcomes during a Watch and Wait Approach for Follicular Lymphoma: A Study from the Australasian Lymphoma Alliance
Authors: Barge Luani , Tobin Joshua W.D. , Waters Niamh , Salvaris Ross , Lai Sam , Potezny Tessa , Cashman Helen , Nguyen-Ngo Caitlyn , Lee Denise , Yannakou Costas K. , Hamad Nada , Tam Constantine S. , Bhattacharyya Abir , Cheah Chan Y. , Morris Kirk , Hawkes Eliza A. , Hapgood Greg 
Published: December 2024

Background: Watchful waiting (WW) in follicular lymphoma (FL) defers treatment and has been considered safe. There are heterogeneous practices regarding follow up and the use of imaging during WW. An assessment of the risks and real-world practices during WW has not been undertaken. GELF criteria have been used to identify low tumour burden FL patients for observation. Some baseline characteristics have been shown to be associated with time to treatment (TTT); however, to our knowledge, no model exists to predict the expected duration of observation prior to treatment for patients undergoing WW.

Aims: We examined the risks of a WW approach and the practices and outcomes for patients with FL managed with a WW approach in the rituximab era. Based on these results, we aimed to develop a risk score to predict TTT for low tumour burden FL patients.

Methods: We conducted a retrospective analysis of patients with newly diagnosed grade 1-3A FL managed with a WW approach across eight academic centres within the Australasian Lymphoma Alliance. Baseline clinical, imaging and laboratory values, treatment details and outcomes were collected. The findings from each clinic appointment and subsequent imaging were assessed for features of progression. Cox regression models were used to identify potential independent prognostic factors associated with TTT.

Results: 267 patients were included with a median follow-up of 5.5 years. The median age was 64 years, 55% were male, 79% had advanced stage disease. Twenty-eight patients (11%) met ≥1 GELF criteria at diagnosis. The Follicular Lymphoma International Prognostic Index (FLIPI) was low (0-1) in 84/252 (33%), intermediate (2) in 101/252 (40%) and high (&gt;3) in 67/252 (27%).

Median TTT was 4.88 years (95% confidence interval [CI] 4.1-5.6yrs), with 30% continuing WW at 10 years. During observation, patients had a median of 8 clinic appointments (range 1-34) and 2 computed tomography (CT) or positron emission tomography (PET) scans (range 0-14) for FL. Complications, including the development of symptomatic disease, occurred during the WW period in 75 (28%) patients with the most common being transformation (n=34, 13%) and pain/discomfort (12.4%). Other significant complications were hydronephrosis 3% and thrombosis 2%. There was no mortality associated with a WW approach. Imaging prior to treatment was surveillance imaging in 20% and prompted by clinical findings in 80%. Prompted imaging was triggered by symptoms in 55%, examination findings in 21% and blood results in 6% with the remainder representing a combination of these factors. Treatment was commenced in 138 patients. Multiple indications for treatment initiation were recorded where applicable. The indication for treatment was increasing tumor volume in 53 patients (38%), symptomatic disease in 38 (28%), transformation in 34 (25%), organ compromise in 24 (17%), potential organ compromise due to tumor location in 10 (7%), cytopenias in 9 (7%) and patient preference in 1 (&lt;1%). Excluding patients with transformation, 68% (71/104) fulfilled GELF criteria at the time of treatment. GELF criteria at diagnosis was not associated with treatment initiation, complications or transformation during WW. Overall survival was similar for patients treated vs ongoing WW (p=0.61).

For GELF negative patients (n=230), &gt;4 nodal stations and elevated LDH were independent prognostic factors for TTT (HR 1.71 (95% CI 1.20-2.42) and 1.80 (95% CI 1.14-2.85), respectively). This identified 3 groups with low (score 0, n=136), intermediate (score 1, n=82) and high (score 2, n=12) risk of treatment initiation with a TTT of 7.94 years (95% CI 4.78-11.10 years), 3.67 years (95% CI 1.54-5.79 years) and 1.38 years (95% CI 0.67-2.11 years), respectively (p&lt;0.001). This model is currently being examined in an external cohort of 201 GELF negative patients managed with WW from 4 French centers. Total metabolic tumor volume (TMTV) has been described as a predictor of TTT. Analysis of TMTV in 106 patients in our cohort is in progress. We are examining the prognostic value of an established threshold of 14cm3.

C onclusion: Current practices for patient selection and management are safe with few major complications during WW. LDH and number of nodal stations at diagnosis identified a low-risk group with prolonged TTT and a high-risk group predicted for early progression who may be candidates for immediate treatment.