First some background:
Cancer refers to the uncontrolled growth of cells within the human body. This uncontrolled growth leads to what is known as tumors, of which there are two types, benign and malignant. While benign tumors pose no serious threat, malignant tumors are capable of invading and eventually destroying nearby tissue as well as what is known as metastasis, which is the spread of cancer cells to other parts of the body. In breast cancer cells, the receptors for cannabinoids tend to be overexpressed compared to normal breast tissue
The new information:
When the cannabinoid receptors on breast cancer cells are activated, cell growth, division, and migration were inhibited. In this specific experiment, mouse breast cancer models showed a 40-50% reduction in tumor growth and a 65-80% reduction in lung metastasis (spread of cancer to the lungs). Also, in PyMT mouse models, which are analogous to human invasive ductal carcinoma, cannabinoid receptor activation led to a reduction in tumor size and not just growth. This reduction was shown to be the result of programmed cell death, or apoptosis, which the cannabinoids induced.
What this means:
This research shows that cannabinoids could potentially be used to protect against the growth and spread of breast cancer.
Qamri, Z, et al. “Synthetic cannabinoid receptor agonists inhibit tumor growth and metastasis of breast cancer.” Molecular cancer therapeutics. 8.11 (2009): 3117-29.