Abstract
In the Netherlands, the curative treatment of esophageal cancer consists of neoadjuvant chemoradiotherapy followed by surgery during which the esophagus and surrounding lymph nodes are removed. This is an intensive and complex treatment, and only 35% of patients are eligible at the time of diagnosis due to the late onset
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of symptoms. Of patients who do begin this treatment, one in seven does not proceed to surgery, mainly due to the development of metastases during nCRT. Even after a successful surgery, a systemic recurrence occurs in 29% of patients within a year.
The aim of the current thesis was to assess diagnostic options and explore opportunities to improve the selection of esophageal cancer patients that benefit from this curative, but highly invasive treatment. The first part focuses on selecting patients and assessing the effect of neoadjuvant chemoradiotherapy. For example, MRI scans that show significant tumor volume regression during neoadjuvant chemoradiotherapy and subsequent anatomical changes which suggest the possible benefit of adaptive radiotherapy. Additionally, in patients with tumors that invade the airways (T4b) treated with definitive chemoradiotherapy (dCRT), an endobronchial ultrasound after dCRT can aid to objectify tumor invasion in the airways, assessing resectability of these tumors that are often deemed inoperable at diagnosis. Also, circulating tumor DNA can also be used to detect “minimal residual disease” after treatment aiding in the selection of patients that might benefit from additional treatment.
The second part assesses improvements in surgical treatment, including the assessment of a salvage robot-assisted minimally invasive esophagectomy after dCRT in patients with cT4b tumors. Results demonstrate that an oncological complete resection can be performed in more than 90% of these patients with acceptable complication and promising survival rates. It also demonstrates the presence of lymph node metastasis in the fatty tissue surrounding the thoracic duct (the thoracic duct compartment). Resection of this compartment could contribute to better oncological outcomes. To aid in the routine resection of this compartment a standardized method to resect this compartment during an esophagectomy has been provided. With that, to prevent chylothorax, which is a serious complication associated with the resection of the thoracic duct, the anatomy of the thoracic duct at the level of the diaphragm was assessed. Results demonstrated that the thoracic duct is formed above the diaphragm by multiple abdominal tributaries. Identification of these tributaries might aid in the prevention of chylothorax.
To conclusion, this thesis provides insights in opportunities to improve patient and treatment selection for esophageal cancer, increasing the success rates of curative treatment.
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