One discussion this week included the composition of post-surgical seroma fluid.

Reference: Valeta-Magara A, et al. Pro-oncogenic cytokines and growth factors are differently expressed in the post-surgical wound fluid from malignant compared to benign breast lesions. SpringerPlus. 2015 Sep 5;4:483. doi:10.1186/s40064-015-1260-8.

Summary: Post-operative accumulation of seroma in the surgical cavity following breast cancer surgery varies in incidence from 2.5 to 51 % of patients. Analysis of seroma has shown that it is an inflammatory exudate, classically seen in the first phase of wound repair. Given that seroma is derived from the wound-healing response of tumor-adjacent stroma, Valeta-Magara et al (2015) explored “whether seroma derived from the excision of benign tumors differs from that of malignant tumors, as malignant and benign tumors may activate or influence the adjacent stroma and infiltrating immune cells differently.”

Post-surgical seroma fluids from 59 patients who had undergone either lumpectomy or mastectomy breast surgery were collected at week 1 or 2 post-surgery by percutaneous aspiration.

It was found that surgical cavity seroma from breast cancer patients has ahigher expression of certain tumorpromoting cytokines, including GRO, ENA-78/CXCL5 and TIMP-2, and lower expression of tumor-inhibiting cytokines IGFBP-1, IL-16, IFN-γ, IL-3 and FGF-9, when compared to seroma from non-cancer patients (p.2). Patients with high body mass index also had higher levels of leptin regardless of malignancy.

In conclusion, breast post-surgical tumor cavity contains factors that are pro-inflammatory regardless of malignant or benign disease, but in malignant disease there is significant enrichment of additional pro-oncogenic chemokines, cytokines and growth factors, and reduction in tumor-inhibiting factors. These results are consistent with tumor conditioning of surrounding normal stromal tissue and creation of a pro-oncogenic environment that persists long after surgical removal of the tumor.

The authors also note that a differential expression of the eight factors between benign and malignant seroma fluid offers research hypotheses to be explored further to determine their role in breast tumor progression, local recurrence and metastasis.