ESTRO 2024 - Abstract Book

S2167

Clinical - Upper GI

ESTRO 2024

Yutaro Tasaki 1 , Takuya Yamazaki 2 , Shuhei Miyazaki 1 , Tatsuya Takeda 3 , Mika Nakatake 4 , Daisuke Nakamura 3 , Asuka Takahira 4 , Koichi Honda 5 , Akiko Egawa 1 , Naoyuki Yamaguchi 6 , Kazuhiko Nakao 6 , Ryo Toya 1 1 Nagasaki University Hospital, Radiology, Nagasaki, Japan. 2 Sasebo Central Hospital, Radiology, Nagasaki, Japan. 3 National Hospital Organization Nagasaki Medical Center, Radiology, Nagasaki, Japan. 4 Japanese Red Cross Nagasaki Genbaku Hospital, Radiology, Nagasaki, Japan. 5 Nagasaki University Hospital, Clinical Oncology, Nagasaki, Japan. 6 Nagasaki University Hospital, Gastroenterology and Hepatology, Nagasaki, Japan

Purpose/Objective:

Endoscopic submucosal dissection (ESD) is a potentially efficient curative intervention for superficial esophageal cancer. However, patients with muscularis mucosae (MM) or more profound invasion are more predisposed to lymph node metastasis, which occurs in 10% – 20% of cases of MM or upper submucosal layer (SM1) invasion and 40% – 60% of cases of middle submucosal layer (SM2) or lower submucosal layer (SM3) invasion. Additional treatment, such as chemoradiotherapy (CRT) or esophagectomy is recommended in cases of MM invasion with positive resection margins, lymphovascular invasion (LVI), or SM invasion. However, the combination of ESD and additional CRT is commonly performed for limited primary tumors, and the adequacy of additional CRT after near circumferential or full-circumferential noncurative ESD has not been fully discussed. Therefore, this study aimed to evaluate the efficacy and toxicity of additional CRT for superficial esophageal cancer after near-circumferential or full- circumferential noncurative ESD, which was defined as a mucosal defect measuring ≥3/4 of the esophageal circumference. Between 2012 and 2018, we performed supplementary CRT for superficial esophageal cancer after noncurative ESD in 34 consecutive patients. Of these, 10 were excluded from the study because their mucosal defects occupied less than 3/4 of the esophageal circumference; thus, 24 participants were included in the study. The clinical target volume (CTV) for the primary lesion (CTV-p) was defined as an area of the excision region with a 2-cm margin in the longitudinal direction. The clinical target volumes for the subclinical region (CTV-s) according to the primary tumor sites were supraclavicular, upper mediastinal, and subcarinal lymph node areas for the cervical and upper thoracic tumors; upper-to-lower mediastinal and perigastric lymph node areas for middle thoracic tumors; and middle-to lower mediastinal, perigastric, and celiac artery lymph node areas for lower thoracic tumors. The planning target volumes for primary tumor (PTV-p) and for subclinical regional lymph node areas (PTV-s) were defined as CTVs with 0.5-cm margins. Elective nodal irradiation (ENI) was performed for PTV-p and PTV-s in all patients, and boost irradiation (BI) was performed for PTV-p following ENI in four patients with positive resection margins. The prescription doses of ENI and BI were 41.4 Gy in 23 fractions and 9 Gy in 5 fractions, respectively. Concurrent chemotherapy (a combination of cisplatin (CDDP) or nedaplatin (NDP) and 5-fluorouracil (5-FU)) was administered to all patients, with 15 of them receiving two cycles of CDDP and 5-FU at 4 – 5-week intervals, 2 receiving one cycle of the same regimen, and 7 receiving two cycles of NDP and 5-FU at 4 – 6-week intervals. Material/Methods:

Results:

We included 20 men and 4 women with a median age of 70 (55 – 81) years. All patients had squamous cell carcinoma. Tumor locations were as follows: cervical (1), upper thoracic (2), middle thoracic (12), and lower thoracic (9) with a median tumor diameter of 32 (7 – 59) mm. The pathological invasion depths were the MM in 11 patients,