Tel Aviv Sourasky Medical Center affiliated to the Tel Aviv University, Aviv, Israel.
Am J Clin Oncol. 2020 Dec 1;43(12):902-904. doi: 10.1097/COC.0000000000000774.
The sacrum as radiation target, raises a conceptual question: should the structure be regarded as a single unit or 5 distinct bones. If the entire sacrum must be irradiated there is a higher risk of rectal morbidity.
Images of 53 patients with sacral metastases were reviewed. The extent of sacral involvement was documented. The location of the rectum was recorded relative to the individual sacral bones.
In 37.7% only S1 and S2 were involved by metastatic disease. In 41.5% there was metastatic involvement of S1-S3. In 1 patient there was involvement of S5 only. In 10 cases the entire sacrum was infested by metastatic disease. The rectum never extended to the height of S1. In 38% the upper pole of the rectum reached the S3 level. In toto, there were 64.2% where the inferior extension of sacral metastatic involvement did not overlap the upper pole of the rectum. Palliation of pain was achieved in 19/20 patients treated with partial sacral irradiation.
The distal part of the sacrum is rarely involved in the metastatic process. Avoidance of radiation therapy to the lower sacrum simultaneously enables effective palliation and sparing of the adjacent rectum.
以骶骨为放射靶区，引发了一个概念性问题：该结构应视为单个单位还是 5 个不同的骨头。如果必须对整个骶骨进行照射，则直肠发病率较高的风险。
回顾了 53 例骶骨转移患者的图像。记录了骶骨受累的程度。记录了直肠相对于各个骶骨的位置。
37.7%的患者仅 S1 和 S2 受到转移性疾病的累及。41.5%的患者 S1-S3 存在转移性累及。1 例患者仅累及 S5。10 例患者整个骶骨均被转移性疾病侵犯。直肠从未延伸至 S1 的高度。38%的直肠上极达到 S3 水平。总的来说，有 64.2%的骶骨转移性受累的下极与直肠上极不重叠。20 例接受部分骶骨照射治疗的患者中，有 19 例疼痛得到缓解。
骶骨的远端很少被转移过程累及。避免对骶骨下部进行放射治疗，同时能够有效缓解疼痛并保护相邻的直肠。
