# Perioperative poly(I:C) reverses accelerated tumor growth after surgery in neuroblastoma

## TL;DR

Surgery can speed up tumor growth in children with neuroblastoma, but using poly(I:C) during surgery may help prevent this effect.

## Contribution

The study reveals that surgery accelerates tumor growth in pediatric neuroblastoma and identifies poly(I:C) as a potential perioperative treatment.

## Key findings

- Surgery accelerates MYCN-amplified neuroblastoma tumor growth in mice.
- An intact immune system is necessary for surgery to promote tumor growth.
- Perioperative poly(I:C) treatment reduces surgery-induced tumor growth.

## Abstract

Surgery for local control is a cornerstone of anticancer therapy with demonstrated survival benefit. However, surgery-induced modulation of antitumor immunity may also contribute to cancer progression and relapse. Despite evidence for a pro-tumor surgery effect in adult cancers, there remain significant knowledge gaps as to the influence surgery has on recurrence or metastatic outgrowth in pediatric cancers. High-risk neuroblastoma (HR-NB) is the most common extracranial solid tumor of childhood. While almost all children with HR-NB undergo surgery, nearly 50% suffer metastatic relapse and succumb to their disease. To ascertain if surgery may contribute to recurrence in HR-NB, we developed a mouse model to comprehensively interrogate the systemic effect of surgery on distant tumor growth and immune modulation. This model demonstrated that MYCN-amplified HR-NB tumor growth was accelerated by surgery compared to tumor-bearing mice without surgical stress. Accelerated tumor growth was absent in HR-NB cells engrafted to immune deficient mice, suggesting that an intact immune system may be needed for surgery to exert its pro-growth effect on distant tumor cells. Consistent with that genetic ablation model, flow cytometry measured a decrease in splenic macrophages (Mϕ) and dendritic cells (DC) and an increase in myeloid-derived suppressor cells (MDSC) after surgery. Perioperative treatment with polyinosinic-polycytidylic acid [poly(I:C)] ameliorated surgery-induced tumor growth. These findings provide direct insight into the systemic surgical effect on pediatric solid tumor growth and identify innate immune adjuvants as a potential perioperative treatment to mitigate this effect.