Ladra Matthew M, Mandeville Henry C, Niemierko Andrzej, Padera Timothy P, Friedmann Alison M, MacDonald Shannon M, Ebb David, Chen Yen-Lin, Tarbell Nancy J, Yock Torunn I
Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
The Royal Marsden Hospital, London, United Kingdom.
Int J Radiat Oncol Biol Phys. 2015 Jun 1;92(2):358-67. doi: 10.1016/j.ijrobp.2015.01.049. Epub 2015 Apr 8.
Local control remains a challenge in pediatric parameningeal rhabdomyosarcoma (PM-RMS), and survival after local failure (LF) is poor. Identifying patients with a high risk of LF is of great interest to clinicians. In this study, we examined whether tumor response to induction chemotherapy (CT) could predict LF in embryonal PM-RMS.
We identified 24 patients with embryonal PM-RMS, age 2 to 18 years, with complete magnetic resonance imaging and gross residual disease after surgical resection. All patients received proton radiation therapy (RT), median dose 50.4 GyRBE (50.4-55.8 GyRBE). Tumor size was measured before initial CT and before RT.
With a median follow-up time of 4.1 years for survivors, LF was seen in 9 patients (37.5%). The median time from the initiation of CT to the start of RT was 4.8 weeks. Patients with LF had a similar initial (pre-CT) tumor volume compared with patients with local controlled (LC) (54 cm(3) vs 43 cm(3), P=.9) but a greater median volume before RT (pre-RT) (40 cm(3) vs 7 cm(3), P=.009) and a smaller median relative percent volume reduction (RPVR) in tumor size (0.4% vs 78%, P<.001). Older age (P=.05), larger pre-RT tumor volume (P=.03), and smaller RPVR (P=.003) were significantly associated with actuarial LF on univariate Cox analysis.
Poor response to induction CT appears to be associated with an increased risk of LF in pediatric embryonal PM-RMS.
局部控制仍然是小儿脑膜旁横纹肌肉瘤（PM-RMS）治疗中的一项挑战，局部治疗失败（LF）后的生存率很低。识别有高LF风险的患者是临床医生非常关注的问题。在本研究中，我们研究了诱导化疗（CT）后的肿瘤反应是否可预测胚胎型PM-RMS的LF。
我们纳入了24例年龄在2至18岁之间的胚胎型PM-RMS患者，这些患者均有完整的磁共振成像资料，且手术切除后有大体残留病灶。所有患者均接受了质子放射治疗（RT），中位剂量为50.4 GyRBE（50.4 - 55.8 GyRBE）。在初始CT前和RT前测量肿瘤大小。
幸存者的中位随访时间为4.1年，9例患者（37.5%）出现LF。从CT开始至RT开始的中位时间为4.8周。与局部控制（LC）的患者相比，LF患者的初始（CT前）肿瘤体积相似（54 cm³ 对 43 cm³，P = 0.9），但RT前（pre-RT）的中位体积更大（40 cm³ 对 7 cm³，P = 0.009），且肿瘤大小的中位相对体积缩小百分比（RPVR）更小（0.4% 对 78%，P < 0.001）。单因素Cox分析显示，年龄较大（P = 0.05）、RT前肿瘤体积较大（P = 0.03）和RPVR较小（P = 0.003）与LF的精算风险显著相关。
小儿胚胎型PM-RMS对诱导CT反应不佳似乎与LF风险增加有关。
