Figure 4

Abscopal effects of surgery. A primary tumor is seeded at time t = 0. After 200 days, a second, metastatic site is seeded elsewhere. Following a period of simultaneous growth of both sites, the primary tumor is removed and abscopal responses scored in the distant tumor. (A) Primary breast tumor with metastasis in the lung. The lung tumor demonstrates rapid outgrowth (negative abscopal effect, red−) immediately following surgical removal of the breast tumor, which had previously been inhibiting the lung tumor by the redistribution of T cells activated by the breast to the lung. (B) Primary breast tumor with lung metastasis, and surgical removal of the lung tumor. The breast tumor is shrinking (abscopal effect, green+) immediately following surgical removal of the lung tumor, which had previously promoted breast tumor by the redistribution of T cells activated by the breast to the lung. (C) Primary lung tumor with breast metastasis, and surgical removal of the breast tumor. Systemic consequences as in panel A. (D) Primary lung tumor with metastasis in the breast. Systemic consequences as in panel B. Dashed lines show the trajectory of tumors without treatment.