MILWAUKI, WI — Cancer associated macrophage-like cells (CAMLs) circulate in the blood of patients with solid tumors such as renal cell carcinoma and thyroid, lung, prostate, pancreatic, and esophageal cancer. A type of circulating stromal cell, CAMLs arise as part of an innate immune response, which could make them useful for predicting the presence of cancer. That would be particularly useful as the cells can be isolated from peripheral blood, making a test non-invasive.

Of course, that’s only true if the cells occur uniquely or disproportionately in patients who have cancer.

Turns out, they do.

That’s the outcome of a study presented as a poster during the 2020 American Society of Clinical Oncology Annual Meeting held May 29-31 by an international team that included Susan Tsai, MD, MHS, of the Clement J. Zablocki VA hospital in Milwaukee, WI.1

The researchers screened the peripheral blood of 308 newly diagnosed cancer patients as well as 39 patients recently diagnosed with non-malignant diseases such as lupus and benign cysts and 76 healthy controls. They found CAMLs occurred in a very high percentage of cancer patients, relatively few patients with non-malignant conditions, and none of the healthy individuals.

The cancer patients had a variety of malignancies including lung (65), pancreas (53), breast (52), prostate (40), esophagus (30), renal cell (18), and hepatocellular (15) cancers as well as neuroblastoma (10), melanoma (8), and other cancers (17). The cancer patients were roughly equally split among stages, with 76 having stage 1 disease, 73 with stage 2, 72 with stage 3, and 65 with stage 4 disease.

The other participants screened included 19 women with benign breast masses, 11 with untreated lupus, five with liver cirrhosis, three with benign prostatic hyperplasia (BPH), and one with a viral infection.

The team separated CAMLs from whole peripheral blood using the CellSieve microfiltration technique.

In total, 87% of the cancer patients had CAMLs, with the percentage rising from 80% in stage 1 patients to 97% in those with metastatic cancer. None of the healthy controls or patients with BPH or cirrhosis had any CAMLs. They did occur in 26% of the women with benign breast masses and 18% of patients with lupus.

Overall, the presence of CAMLs proved to have 87% sensitivity and 80% specificity for cancer vs benign conditions, for a positive predictive value of 97% and negative predictive value of 43%.

The researchers concluded that CAMLs were a “sensitive blood-based biomarker found in all stages of cancer that is rare in non-malignant conditions and absent in healthy individuals.”

  1. Adams D, Lin SH, Pass HI, Chumsri S, Lapidus RG, Edelman M, Bergan RC, Tsai S, Aft R, Pillai S, Watson M, Kim AK, Chikamatsu K, Hayashi M, Loeb DM, Pinto NR, Alpaugh K, Tang C-M, Ho TH, Marks JR. “Circulating stromal cells as a potential blood-based biomarker for screening invasive solid tumors.” Abstract 3535. Poster 265. 2020 ASCO Annual Meeting. May 29-31, 2020.