“Our study represents the largest institutional cohort analysis on the course of patients with stage I POAML,” said first author Linrui Gao, MD, of the department of radiation oncology at the National Clinical Research Center for Cancer, Chinese Academy of Medical Sciences and Peking Union Medical College, in Beijing.
Dr. Gao presented these findings at ESMO 2023, held in Madrid.
“We confirm the indolent nature of this stage I disease, with mortality that is similar to the general population and a low rate of lymphoma-attributed mortality,” she said, adding that “radiation therapy was associated with the lowest relapse or disease progression, compared with [other treatments].”
POAML, which can involve lesions in areas including the eyelid, conjunctiva, orbit, and lacrimal gland, makes up about 7% of mucosa-associated lymphoid tissue (MALT) lymphomas. However, the incidence is reported to be steadily increasing. With the majority of patients, 70%-85%, diagnosed as stage I, consensus on treatment approaches is lacking.
Guidelines typically recommend radiation therapy as the standard of care, and approximately 70% of POAML patients do receive the therapy, compared with only about 36% of those with early-stage MALT lymphoma, with the indolent nature of the disease likely weighing on decisions to forgo the treatment, Dr. Gao reported.
“Adoption of initial radiotherapy in early-stage POAML is relatively low worldwide, with possible reasons being [concerns] of a low survival benefit and long-term toxicities,” she said.
To evaluate the long-term outcomes based on baseline clinical features and treatments, Dr. Gao and colleagues conducted a retrospective study of 262 patients with stage I POAML (ipsilateral or bilateral disease), enrolled between January 2000 and December 2020 at two hospitals in China.
Of the patients, who had a median age of 55 and a male-female ratio of 1:3, 82 were initially treated with radiation therapy, 81 with observation, 70 with surgery, and 29 with systemic treatment.
Those receiving radiation therapy had higher rates of an Eastern Cooperative Oncology Group performance status of 1 or higher (P = .02), higher elevations of LDH (P = .03), and higher rates of chronic disease (P < .001), while other baseline characteristics between the groups, including age, T stage, symptom duration, and other factors, were similar.
With a median follow-up of 66 months, the 5-year and 10-year overall survival rates were 96.8% and 90%, respectively, which is similar to the survival rate in the general population in China.
Likewise, the 5- and 10-year rates of lymphoma-specific mortality were both extremely low, at 0.4%, and the corresponding rates of competing nonlymphoma mortality at 5 and 10 years were 2.3% and 4.2%, also consistent with the general population.
The 5- and 10-year mortality rates remained similar to the general population in stratifying patients according to the initial treatment type (P = .767 between treatments).
In terms of recurrence, the overall failure rates were relatively high, with 19.5% of patients experiencing relapse at 5 years and 24.05% at 10 years.
“The failure rates show that the risk of relapse in POAML does not decrease over time,” Dr. Gao said.
Notably, those treated with radiation therapy had a significantly decreased 5-year cumulative risk of failure (8.5%), compared with those who only received observation (29.6%), surgery (22.9%), or systemic treatment (17.2%; overall, P = .002).
The most common failure site was the ipsilateral orbit, and again, rates of those relapses were significantly lower with radiation therapy (2.4%), compared with observation (23.5%), surgery (21.4%), and systemic treatment (17.3%).
However, rates of relapses in other sites, including the contralateral orbit, extraocular site, and multiple sites, were similar among all treatment groups. One patient receiving systemic treatment had large cell transformation, associated with poorer outcomes.
Strategies after recurrence were salvage therapy for 53 patients, including 27 receiving radiation therapy, and observation for 10 patients.
Dr. Gao noted that treatment failure was not associated with higher mortality rates. “However, given the limited number of cases, we think more cases and longer follow-up are needed,” she told MDedge.
Among the most common acute toxicities were ocular dermatitis or mucositis, described as mild, among 23 patients receiving radiation therapy. Nine patients experienced postoperative complications of mild eye irritation and periorbital edema, and five patients receiving systemic treatment experienced grade 2-3 leukopenia. There were no severe adverse events.
In terms of late ocular adverse effects, overall, 3 patients in the radiation therapy group developed cataracts and 143 patients developed dry-eye disease.
“Radiation therapy was associated with the lowest rate of relapse progression, compared with observation, surgery, and systemic treatment, with similar overall and recurrent survival,” Dr. Gao said.
“Based on our study results, radiotherapy should be considered as the optimal treatment for all patients with stage I disease because of its lowest failure risk and minor toxicity,” Dr. Gao told MDedge.
“However, the radiotherapy dose and techniques should be further optimized in good clinical trials,” she noted. “There are some clinical studies undergoing to explore the modern radiotherapy strategy, including by our group.”
Commenting on the study, discussant Olivier Casasnovas, MD, PhD, of the department of hematology, University Hospital Francois Mitterrand, in Dijon, France, noted that “interestingly, radiotherapy reduced the risk of local relapse but not systemic relapse.”