Higher or lower radiotherapy dose for patients with non-Hodgkin lymphoma undergoing stem cell transplantation?

This study examined how effective and safe a higher radiotherapy dose was for patients with non-Hodgkin lymphoma (NHL) undergoing stem cell transplantation (SCT). The authors found that patients who received a lower radiotherapy dose survived longer and had fewer side effects than the higher dose.

NHL is a cancer of immune cells. Chemotherapy and radiotherapy (RT) can be used to kill NHL cells. SCT involves taking immune cells from the patient or healthy donors and giving them to patients after they have received chemotherapy and RT. This replenishes healthy immune cells. RT can also be used to prevent graft versus host disease (GVHD). GVHD is a complication of SCT where the transplanted cells fight the patients' bodies. 

This strategy is effective for many patients. Some patients, however, cannot receive a full dose of chemotherapy because of their age (over 65) or because of other health conditions. These patients receive a low dose of chemotherapy. It is unclear if a higher dose of RT can be effectively and safely used in these patients instead.

Data from 413 patients with NHL were examined. 349 patients received chemotherapy, SCT, and low-dose RT and were followed for 59.4 months. 64 patients received chemotherapy, SCT, and high-dose RT and were followed for 48.5 months.

Patients who received low-dose RT had a 51% higher chance of survival than high-dose RT. After 5 years, 51% of the low-dose group had survived compared to 31% of the high-dose group.

There was little difference between the groups in terms of the number of patients who did not experience a worsening of NHL. After 5 years, 37% of the low-dose group and 29% of the high-dose group had survived without cancer worsening. 

The number of patients who developed GVHD was similar between the two groups. After 180 days, 46.6% of the low-dose group and 50% of the high dose group had developed GVHD.

The authors concluded that low-dose RT improved the outcomes of patients with NHL undergoing SCT with reduced-dose chemotherapy.

This study was based on medical records data, meaning that not all information was available. There were unequal numbers and small numbers of patients in each group meaning that comparisons are difficult.