Lymphoma patients on proton therapy mostly young with lower mediastinal involvement

Proton therapy-treated patients with mediastinal lymphoma, in general, are young and have lower mediastinal involvement, reports a study.

In addition, nearly all treated patients within a prospective, multi-institutional proton registry fit the consensus recommendations published in 2018 by the International Lymphoma Radiation Oncology Group (ILROG) as regards which patients may most benefit from the said treatment.

Patients were included in the analysis if they had lymphoma of the mediastinum treated exclusively with proton therapy, and if their digital imaging and communications in medicine (DICOM) treatment data were available for review.

The authors used the inferior-most aspect of the left pulmonary artery (PA) as a surrogate, given the challenge with reliably visualizing the left mainstem coronary artery. They described the extent of disease as upper mediastinum (above the level of left PA), middle mediastinum (below left PA but at or above the level of T8), or low mediastinum (below T8).

Fifty-six patients met the eligibility criteria and were treated between November 2012 and April 2019. Those who received proton therapy were typically young (median age 24 years, range 12–88), with more than half being female (55 percent). Most patients were treated at initial diagnosis (86 percent) and had Hodgkin lymphoma (79 percent).

Nearly all patients (96 percent) had mediastinal disease extending down to the level of the heart: 48 percent had middle and 48 percent had low mediastinal involvement. Most of them (96 percent) also met the ILROG consensus recommendations: 95 percent had lower mediastinal disease, 46 percent were young females, and 9 percent were heavily pretreated.

Of note, heart and lung dose significantly correlated with the lowest extent of mediastinal disease.