Comparing two doses of radiotherapy for slow-growing non-Hodgkin lymphomas.

The authors compared a high-dose radiation (24 Gy) in 12 parts with a low-dose radiation (4 Gy) in 2 parts in patients with slow-growing non-Hodgkin lymphomas (NHLs).

The study found that the best radiotherapy dose for slow-growing NHLs is 24 Gy in 12 parts after a 5-year follow-up.

The current standard of care for slow-growing NHL such as follicular lymphoma (FL) or marginal zone lymphoma (MZL) is 24 Gy in 12 sessions. However, some small studies showed that a smaller dose of radiations of 4 Gy in two sessions may offer the same effectiveness in the short-term.  

The best radiotherapy dose for slow-growing NHLs in the long-term remains uncertain.

548 patients with slow-growing NHL (FL and MZL) were included in this study. They were randomly divided in to two groups to receive either 24 Gy in 12 fractions or 4 Gy in 2 fractions. The average follow-up time was 73.8 months.

After 5 years, 89.9% of the 24 Gy group were alive without disease worsening compared to 70.4% in the 4 Gy group. Patients who received 24 Gy were 3.46 times more likely to have better survival without cancer worsening after 5 years.

In patients with MZL, 100% were alive without cancer worsening after 5 years in the 24 Gy group compared to 88% in the 4 Gy group. In patients with FL, 88.2% of the 24 Gy group were alive after 5 years without cancer worsening compared to 67.5% of the 4 Gy group.  

There was no difference in overall survival between groups. The 5-year overall survival rates were 75.1% in the 24 Gy group and 77.6% in the 4 Gy group.

Medium to severe side effects were reported in 10% of patients in the 24 Gy group and 4% of the 4 Gy group. The most common side-effects were hair loss, dry mouth, fatigue, mouth sores, and pain. 

This study showed that 24 Gy in 12 sessions was the most effective, tolerated treatment for patients with slow-growing NHLs in the long-term.