Monitoring breast cancer therapy with disseminated tumor cells

This paper studies whether disseminated tumour cells can be used as an indicator in monitoring breast cancer treatment. 

Disseminated tumor cells (circulating cancer cells in secondary organs, bone marrow or blood) can be present in the bone marrow of patients with breast cancer. Presence of disseminated tumor cells in a patient often indicates a poor prognosis (disease outcome); even after removal of the tumor breast cancer can relapse. Adjuvant therapy (additional therapy that is given after primary treatment) can be used to eradicate persistent minimal residual disease, but there are currently no methods to monitor how effective adjuvant therapy is.

The authors evaluated whether disseminated tumor cells are a useful marker to monitor adjuvant cancer treatment.

Women who were treated for early stage breast cancer were included in the study. During their initial diagnosis and surgery, bone marrow aspiration (removal of bone marrow from bone) was performed. Bone marrow was processed to detect disseminated tumor cells. Disseminated tumor cell positive patients (those with the presence of disseminated tumor cells) were offered a second and third bone marrow aspiration. Patients also had to receive adjuvant systemic therapy (hormone and/or chemotherapy with or without trastuzumab; Herceptin) to be included in the analysis. 

190 patients were included in analysis. 83% of patients received adjuvant endocrine (hormone) therapy, 52 % received adjuvant chemotherapy, and 72 % received adjuvant bisphosphonate therapy (used to prevent the loss of bone mass).

At the second bone marrow aspiration, disseminated tumor cells were present in 35 (18%) of patients. 71 patients received a third bone marrow aspiration. Disseminated tumor cells were present in 11 (16%) of patients.

At the third bone marrow aspiration, disseminated tumor cells were associated with the patient’s estrogen receptor-status and endocrine treatment. The estrogen receptor (ER) positive or negative status of the patient typically determines type of therapy patients receive. 39% of ER-negative patients were disseminated tumor cell-positive, whereas of 11% of ER-positive patients were disseminated tumor cell-positive. 42% of patients not receiving endocrine therapy were disseminated tumor cell-positive, and 10% of patients receiving endocrine therapy were disseminated tumor cell-positive.

Those testing positive for disseminated tumor cells at the second bone marrow aspiration were 4.17 times more likely to experience disease recurrence (return) and 5.02 times more likely to experience mortality (death) than those who tested negative. Those testing positive for disseminated tumor cells at the third bone marrow aspiration were 3.2 times more likely to have a shorter disease-free survival compared to those who tested negative.

The authors concluded that a majority of initially disseminated tumor cell-positive patients become disseminated tumor cell-negative during adjuvant therapy. Persistent disseminated tumor cells may indicate that patients are not responding to systemic treatment.

There may be bias involved in the study as not many patients underwent the third bone marrow aspiration.