Some info on CTC count and significance

I am sharing some notes from papers on the importance of CTC as we go along with results from other patients. The bottom line is that if a drug can reduce the CTC can extend the life of a patient, that is, in Oncology, the drug is doing its job and has therapeutic effect. . Emphasis are mine:

Hematogenous spread is the main means and pathway for distant metastasis of breast cancer, and micrometastasis of breast cancer cells entering the peripheral blood is the main mechanism for distant metastasis. Breast cancer cells in peripheral blood can reach a variety of tissues and organs through blood circulation, in which bone and lung are the main sites of distant metastasis.

Tumor cells divide from tumor tissue and enter the blood circulation, and then form tumor embolisms through migration, adhesion, and aggregation in the blood circulation. The above process is the main type of distant metastasis of breast cancer, and is also an important factor that affects the survival and prognosis of patients. Therefore, the detection of circulating tumor cells in peripheral blood of breast cancer patients plays an important role in breast cancer diagnosis, prognosis assessment, selection of treatment regimen, and prediction of metastasis and recurrence.

Relationship between CTC level versus survival and prognosis of patients

A multicenter study carried out by Banys et al. demonstrated that the survival and prognosis of breast cancer patients with the CTC level greater than 5 in 7.5-ml blood samples are significantly worse than in patients with CTC level less than 5.

For most tumors, once distant metastasis occurs, the difficulty of treatment greatly increases and the efficacy and prognosis are worse. More than 90% of deaths in patients with malignant tumors are caused by distant metastasis and recurrence of tumor cells. Hematogenous dissemination is an important mode of distant metastasis of breast cancer. The distant metastasis of tumor cells can occur even in the early stage of breast cancer. The spreading of breast cancer cells from the primary focus and then entering the blood circulation to form CTC are the first links in distant metastasis. Detection of changes in CTC number and dynamic states can reflect tumor loading, provide early prediction of the recurrence and metastasis of non-metastatic breast cancer, monitor the development of the disease, and help clinicians to choose treatment options and take effective intervention measures to block the metastatic focus formation, and thus is important in controlling the disease, reducing recurrence, providing high curative effect, and improving prognosis. Therefore, the diagnostic and predictive value of CTC and its role in the transformation of medical research have attracted more and more attention from medical science researchers, and are now popular topics in the field of cancer research.

From a Paper by Dr. M Cristofanilli

In a prospective, multicenter study, we tested 177 patients with measurable metastatic breast cancer for levels of circulating tumor cells both before the patients were to start a new line of treatment and at the first follow-up visit.

CONCLUSIONS

The number of circulating tumor cells before treatment is an independent predictor of progression-free survival and overall survival in patients with metastatic breast cancer.

Although some of the clinical factors remained relevant in the multivariate analysis (e.g., time to metastasis, HER2/neu status, and type of therapy), the levels of circulating tumor cells at baseline and at the first follow-up visit emerged as the strongest predictors of progression-free and overall survival

The results of this trial indicate that in metastatic breast cancer the level of circulating tumor cells before a new therapy is initiated and, even more important, the level measured at the first follow-up visit are useful predictors of progression-free survival and overall survival.

Circulating tumor-cell levels of ≥5 cells per 7.5 ml of blood

In a multivariate analysis, the predictive value of the level of circulating tumor cells, either at baseline or at the first follow-up visit, was independent of the time to metastasis, the site of metastasis (visceral as compared with nonvisceral), and hormone-receptor status.