Case Report: Retrospective surgeon-guided reassessment of clinical target volume delineation in low-dose radiotherapy for postoperative chylothorax: an eight-patient case series.

BACKGROUND

Postoperative chylothorax is an uncommon but challenging complication after thoracic surgery. Low-dose external beam radiotherapy (RT) has been proposed as an adjunct treatment when conservative management or surgical intervention fails, but factors associated with treatment success remain unclear.

METHODS

We conducted a retrospective case series of eight patients with persistent postoperative chylothorax treated with RT at a single institution (January 2019-July 2022). All patients received low-dose RT (9 Gy in 1.5-Gy fractions or 10 Gy in 2-Gy fractions). To explore factors associated with outcomes, thoracic surgeons retrospectively reviewed surgical dissection fields and re-contoured clinical target volumes (CTVs), which were compared with delivered RT isodose distributions.

RESULTS

Chylothorax resolved without recurrence in 4 of 8 patients (50%). Patients with extremely high baseline chyle output (e.g., >1,500 mL/day) showed limited response to RT despite apparently adequate overall isodose coverage. Retrospective plan review also demonstrated incomplete inclusion of surgically dissected lymphatic regions within the RT field in several unsuccessful cases.

CONCLUSION

This case series highlights the value of retrospective surgeon-guided CTV reassessment in identifying clinically relevant coverage gaps in postoperative chylothorax treated with low-dose RT. In this series, patients with high output (>1,500 mL/d) had poor responses to RT, suggesting that earlier surgical intervention may be warranted in selected cases; however, this observation requires validation in larger cohort.