T. I. Bogatyreva, V. V. Pavlov, A. Yu. Terekhova, S. S. Shklyaev, N. A. Falaleeva
A.F. Tsyb Medical Radiological Research Centre - branch of the NMRC of Radiology of the Ministry of Health of the RF, Obninsk, Russia
Background: Hodgkin lymphoma (HL) commonly involves the mediastinum and late effects from treatment can cause significant problems. At MRRC consolidative IFRT to 20 Gy in accelerated hyperfractionation regimen (AHFX, 2 daily fractions 1,3–1,5 Gy with the interval 4.5 hours) versus 40 Gy in conventional fractionation (CF) had been explored since 1988 in clinical trials of I-II and III phase. With the similar rate of local control, the AHFX regimen spared organs at risk (lung and heart) and underlying bone marrow from irreversible aplasia. After 2010 AHFX has been modified for ISRT.
Aims: To evaluate local control of mediastinal involvement in HL patients with different AHFX regimens depending on the size of residual tumor.
Methods: Between 1998 and 2015, total 372 patients with HL IIXE, III-IV stages received mediastinal irradiation after partial response to the first-line chemotherapy (ABVD, BEACOPP-21 or BEACOPP-14, depending on prognostic group). Before 2010, 20 Gy were delivered with two radiation techniques: 1 gr. (150 pts) received dose fractions of 1,5 Gy+ 1,5 Gy as IFRT; 2 gr. (48 pts with locally advanced disease) received 1,25 Gy+1.5 Gy; the first of two daily fractions encompassed half-thorax or whole thorax (15 Gy/12 days) and the second fraction was delivered through standard mediastinal field (9 Gy/6 days). After 2010, ISRT was delivered with dose fractions of 1,3Gy+1,5Gy (3 gr.,116 pts); controls (4 gr., 58 pts) received 30–36 Gy CF. The main end-point was local relapse (LR) rate within irradiated mediastinal field.
Results: With median follow-up 60 months for gr.1 and gr.2, the 10-year OS was, respectively, 92% and 89%; the 10-year FFP was 89% and 87%. The LR rate in irradiated mediastinum for gr.1 and gr.2 was 7% and 12%. Local control by maximum diameter of residual tumor in gr.1 and gr.2 was as follows: < 2,0 cm, 93% vs. 100%; 2,1 to 4,9 cm, 91% vs. 86%, ≥5 cm, 86% vs. 87% (n.s.). Median follow-up for gr.3 and gr.4 was 24 months; the LR rate was, respectively 4% and 7%.
Conclusions: Our data showed that low-dose AHFX consolidation was efficient, with long-lasting effects in the majority of patients with residual and refractory mediastinal masses. Tumor masses ≥5 cm at the start of RT had not impaired local control.