Breast cancer surgery remains the first line of defence for most patients suffering from the disease. However, the specific type of surgery and whether other treatments will be necessary depends heavily on the molecular subtype of the tumour. An integral molecular marker in this case is hormone receptor status, which indicates whether the breast cancer cells contain certain receptors for the hormones estrogen and progesterone.

What is hormone receptor status in the case of breast cancer?

Hormone receptors are special proteins found in and on the surfaces of malignant cells. These receptors are like the sensory organs of the cells, responsible for delivering signals from the hormones and bloodstream. These receptors act like an on-off switch for the cells. If the hormonal signal reaches the receptors, sometimes they can set off further growth in the malignancy of the tumour. If the receptor proteins in the breast cancer cells react to the hormonal signals, they are called hormone-receptor-positive. When they do not respond to the corresponding signals, they are called hormone-receptor-negative.

The testing for hormone receptor status in breast cancer

A breast cancer specialist usually conducts a staining process named immunohistochemical staining assay or ImmunoHistoChemistry (IHC) to determine the hormone receptor status. Testing breast cancer specimens for hormone receptor status provides useful insights for guiding surgical decisions and adjuvant systemic therapies. The majority of breast cancers are hormone receptor-positive, meaning the cells contain estrogen and/or progesterone receptors. This implies the cancer cells may receive signals from these hormones promoting growth.

In contrast, hormone receptor-negative breast cancers lack estrogen and progesterone receptors. This means tumour growth is not driven by hormonal signalling. Compared to hormone receptor-positive disease, hormone receptor-negative cancers tend to be more aggressive and fast-growing.

Treatment for hormone-receptor-positive breast cancer

Most often, hormone receptor-positive breast cancers are treated with breast-conserving lumpectomy to remove the tumour, followed by radiation therapy. However, mastectomy may be required if the cancer is large and multifocal.

Furthermore, adjuvant hormonal therapy nearly always follows surgery for hormone receptor-positive breast cancers. Medicines such as tamoxifen, aromatase inhibitors, or ovarian suppressors block estrogenic signalling, which fuels tumour growth. Providing this systemic treatment reduces the risk of recurrence.

Treatment for hormone-receptor-negative breast cancers

In this case, there is little to no choice of impeding the malignancy growth through controlling the hormonal level. For hormone receptor-negative breast cancer, mastectomy is more commonly recommended as breast-conserving surgery can be riskier. Research shows more local recurrence rates for hormone receptor-negative cancers treated with lumpectomy and radiation compared to mastectomy.

As stated earlier, hormone receptor-negative cancer does not respond to hormonal therapies. Instead, systemic treatment relies more heavily on chemotherapy, which can be effective regardless of receptor status.

The relation between hormone-receptor status and surgery

The correlation between receptor status and recommended surgery is not absolute. Tumor size, lymph node involvement, patient preferences, and other clinical variables also guide surgical decision-making. Nevertheless, receptor status remains integral for informing appropriate systemic treatments to reduce recurrence risk following breast cancer surgery.

While hormone receptor status is relatively binary, some key nuances exist. Firstly, receptor status can change over the course of the disease. Cancers may lose hormone receptor expression or vice versa. Secondly, low receptor positivity can occur. Even if 1% of cells are receptor-positive, targeted endocrine therapies may confer some benefit.

Due to the aforementioned factors, according to a breast cancer surgeon, repeat receptor testing is important, particularly if the disease recurs. Biopsy of suspected metastases should include hormone receptor analysis for potential treatment implications. For example, a receptor-negative primary breast tumour that has become receptor-positive over time could now benefit from hormonal therapy.

In conclusion, surgery represents a major treatment component for most breast cancers regardless of receptor status. However, the specific operation undertaken and subsequent adjuvant therapies are largely determined by whether the tumour is hormone receptor-positive or negative. Receptor testing provides key biological insights to customize treatment by surgery and systemic approaches for the best outcome.