[乳癌] 術中放射治療

乳癌的術中放射治療, 其意義為在乳癌手術中, 進行一次性的術中放射治療(prepatholgy), 或是在術後確認病理分期的時候,再打開傷口把放射治療器具放入(postpathology), 利用一次的治療來節省病人的時間, 但成效究竟如何呢, 以下是相關論文整理

1. Targit-A: 為英國針對早期乳癌病人, 45歲以上, unifocal lesion, 排除lobular carcinoma, 利用50 KV x ray(orthovoltage)技術進行治療, 其劑量為20Gy/1Fr,  使用non-inferiority trial design, 其結果如下:

接受乳房手術	Targit(single-dose targeted intraoperative radiotherapy)	EBRT
5-year risk for Local recurrence (median follow-up: 2y5m)	3.3%	1.3%
p=0·042
breast cancer mortality	2.6%	1.9%
p=0.56
non-breast-cancer deaths	1·4%	3·5%
p=0·0086
Overall mortality	3.9%	5.3%
p=0·099
grade 3 or 4 skin complications	4	13
p=0·029

 如果用subgroup分析5-year risk for Local recurrence的話:
prepathology   v.s. EBRT: 2·1% vs 1·1% (p=0·31)
postpathology v.s. EBRT: 5·4% vs 1·7%  (p=0·069)

結論: IORT 可以在prepathology的情況下, 被考慮當作體外放射治療的替代治療

JAMA oncology在2020年發表了長期追蹤的結果[3], 主要是針對post-pathology的部分, 發現在long-term (median = 9 yrs) mastectomy-free survival, distant disease-free survival, and overall survival 沒差, 但是locoregional recurrence, postpathology-IORT 還是比較高

BMJ 在 2020 年也發表了長期追蹤的結果, 主要是針對pre-pathology的部分, 結果發現 IORT 在 local control, mastectomy-free survival, distant disease-free survival, overall survival, and breast cancer mortality 都跟 EBRT 差不多, 在non-breast cancer mortality 方面來說還比較低

=> Targit-A 以結果來說, 比較傾向使用Pre-pathology, 如果因為某些因素使用post-pathology IORT的話, 就要付出local control 比較差的代價


2. Milan ELIOT trial:

接受乳房手術	IORT with electron	WBRT+boost
Ipsilateral breast tumor recurrence (IBTR) – 5 year event rate	4.4%	0.4%
Hazard ratio=9.3 [95% CI 3·3–26·3]
5-year overall survival	96.8%	96.9%
p=0.56
Fewer skin side effect in IORT(p=0.0002)

reference:

1. Vaidya, Jayant S., et al. "Risk-adapted targeted intraoperative radiotherapy versus whole-breast radiotherapy for breast cancer: 5-year results for local control and overall survival from the TARGIT-A randomised trial." The Lancet 383.9917 (2014): 603-613.

2. Veronesi, Umberto, et al. "Intraoperative radiotherapy versus external radiotherapy for early breast cancer (ELIOT): a randomised controlled equivalence trial." The lancet oncology 14.13 (2013): 1269-1277.

3. Vaidya, Jayant S., et al. "Effect of Delayed Targeted Intraoperative Radiotherapy vs Whole-Breast Radiotherapy on Local Recurrence and Survival: Long-term Results From the TARGIT-A Randomized Clinical Trial in Early Breast Cancer." JAMA oncology (2020): e200249-e200249.

4. Vaidya JS, Bulsara M, Baum M, et al. Long term survival and local control outcomes from single dose targeted intraoperative radiotherapy during lumpectomy (TARGIT-IORT) for early breast cancer: TARGIT-A randomised clinical trial. BMJ. 2020;370:m2836. Published 2020 Aug 19. doi:10.1136/bmj.m2836