Clinical Features, Outcomes and Prognosis of Oropharyngeal Lymphoma: An Analysis from the Thai Lymphoma Study Group (TLSG)

OBJECTIVE: To analyze clinical features, outcome of treatment and prognosis of Thai patients with oropharyngeal diffuse large B cell lymphoma (DLBCL).

METHODS: From the nationwide multicenter registry of 4,371 newly diagnosed lymphoma patients in Thailand between 2007 and 2014, there were a total of 2,399 DLBCL patients. The patients who have oropharyngeal lesions were collected. Clinical profiles and response to treatment and outcome were analyzed.

RESULTS: Among 2,399 DLBCL patients, 1664 cases(69.4%) had extranodal lesions. The five most common site of extranodal involvement were oropharyngeal, stomach, intestine, sinonasal cavity and breast. There were 193 cases with oropharyngeal lesions accounted to 11.6% of DLBCL with extranodal lesions. The median age was 58 years (range17-91).Fifty percent of patients were male. B symptoms were presented in 39.9%. Most common sites of involvement were tonsils (81.8%) and base of tongue (15.0%) Majority of patients presented with stage I-II ( 21.2%, 43.0%) , 38.8% presented with advanced stage. Eighty three percent of the patients had ECOG score 0-1. Majority of the patients have IPI< 2 (74.6%). Ninety four percent of the patients received chemotherapy, the most common regimen was CHOP (96.0%), Rituximab was given in 29.1%. Intrathecal methotrexate was given in 8.9% Radiation therapy combine with chemotherapy was used in 16.0%, 2.7% received only local radiation therapy and 2.7% received only palliative care . Among those who received curative aim treatment,the overall response rate was 87.1% (CR 78.4 %). With a median follow-up time of 46 months (range 4-91 months) , median overall survival (OS) was 50.3 months and median progression free survival(PFS) was 31.5 months. The multivariate analysis revealed IPI>2, age>60 years and stage >2 associated with poor OS (HR 2.98, CI: 1.93-4.61, p=0.000, HR 2.79, CI:1.67-4.68, p=0.000 and HR 1.79,CI:1.09-2.97, p=0.002) but only age and IPI was significantly associated with PFS (HR 2.79,CI: 1.28-6.06, p=0.10, HR 2.86, CI:1.37-5.97, p=0.005). Advanced stage trended to associated with poor PFS but did not reach statistical significant (HR 1.90,CI:0.95-3.79, p=0.07). Rituximab significantly improved both OS and PFS (HR 0.58, CI;0.33-0.99, p=0.046 and HR 0.44, CI; 0.19-1.0, p=0.05) but radiotherapy did not improved outcomes(HR1.05,CI:0.56-1.99, p=0.87). The patient who received intrathecal methotrexate had poor outcome (HR 3.43,CI: 1.57-7.50, p=0.004)

CONCLUSION: Comparing to other Thai patients with DLBCL , those with orpharyngeal lesion have similar prognosis. Receiving Rituximab improved outcomes. Different from international data, combination chemo-radiotherapy and intrathecal chemotherapy were not routinely practice and did not relate with good outcomes. This may be caused by limited resource of radiotherapy in Thailand so it was reserved for only patients with bulky mass or impending airway obstruction.