"Determining the stage of breast cancer is a crucial process," says Dr. Han Mei, a breast oncologist at Houston Methodist Hospital. "It helps us assess the extent of the cancer—whether it is localized to breast tissue or has spread beyond the breast—and assists us in planning the most appropriate treatment."
Knowing the breast cancer stage provides a roadmap for discussions with your doctor, helping you ask relevant questions and find appropriate support resources. On a positive note, the mortality rate for women diagnosed with new or recurrent breast cancer is less than 3%.
How is breast cancer staged?
Staging breast cancer requires a comprehensive assessment that analyzes the following key factors:
- Tumor size
- Whether the cancer has spread to nearby lymph nodes
- Whether the cancer has spread to distant organs
- The tumor's molecular subtype (specifically, whether the cancer cells produce certain proteins—such as estrogen receptors, progesterone receptors, and/or HER2)
- Cancer aggressiveness (how aggressive the cancer cells appear under a microscope)
Several tests are used to gather this information, such as mammography, ultrasound, breast biopsy, lymph node biopsy, PET scans, and MRI scans. Not all patients will require every test; their care team will help determine which ones are appropriate for their specific case. Based on the results of these tests, the doctor will determine the stage of the cancer. This helps in explaining the disease and discussing the diagnosis, treatment options, and other matters of importance to the patient.
Breast Cancer Staging
There are five stages of breast cancer, classified using Roman numerals ranging from 0 to IV. Stage 0 refers to non-invasive cancer (*carcinoma in situ*), which is confined to the milk ducts. Stage IV represents the most advanced form—metastatic breast cancer—where the cancer has spread to other parts of the body.
A lower stage number indicates less spread, while a higher number indicates more extensive spread; generally, a higher stage also implies the need for more aggressive treatments.
Breast Cancer Stages Requiring Surgical Removal
Surgery is almost always necessary to treat breast cancer. The only exception is stage IV breast cancer, as surgery rarely plays a role in treating metastatic disease. Dr. May explains that surgery is particularly essential for early-stage breast cancer—stages I and II—because it can completely eliminate the disease.
Small, early-stage tumors can often be removed using a breast-conserving procedure called a lumpectomy, which removes the tumor along with only a small amount of healthy breast tissue. The amount of tissue removed depends on the size of the tumor.
In contrast, a mastectomy involves removing the entire breast and may be used to treat breast cancer ranging from stage 0 to stage III. There are several reasons why a doctor might recommend a mastectomy instead of a lumpectomy, even in early-stage cases. Dr. May explains that if the tumor cannot be removed due to its large size, or if the cancer has spread to cover two-quarters or more of the breast, a mastectomy (breast removal surgery) is required.
Following the mastectomy, breast reconstruction can be performed using either an implant or the patient's own tissue—often harvested from the abdominal area. Newer techniques can also help preserve the nipple and breast skin in certain cases, thereby improving the aesthetic outcome after mastectomy and reconstruction.
Breast Cancer Stages Requiring Chemotherapy and Radiation Therapy
In addition to surgery, most stages of breast cancer require or benefit from chemotherapy and/or radiation therapy. The goal of these treatments is to kill cancer cells or inhibit their growth within the breast tissue. Chemotherapy is administered via medication, whereas radiation therapy utilizes high-energy beams.
These treatments can be used to shrink the tumor prior to surgery or to eliminate any remaining cancer cells post-surgery, helping to prevent cancer recurrence.
"If early-stage cancer is aggressive, we may recommend chemotherapy," says Dr. May. "The benefit of chemotherapy or radiation therapy in other stages of breast cancer depends on several factors, such as the cancer's molecular subtype and the type of breast surgery performed to remove the tumor."
For instance, HER2-positive breast cancer requires chemotherapy. The same applies to triple-negative breast cancer—a less common type of breast cancer that is nonetheless aggressive and lacks the molecular markers often targeted during treatment, such as estrogen receptors, progesterone receptors, and the human epidermal growth factor receptor 2 (HER2) protein.
Dr. May adds, "Radiation therapy is used when a patient undergoes tumor removal surgery. In some cases, patients may also require radiation therapy following a mastectomy." For stage IV breast cancer, chemotherapy is used—provided the patient can tolerate it—to help control the spread of the disease and alleviate symptoms. It is typically combined with other treatments, such as hormonal therapy, targeted therapy, and immunotherapy.
Are the stages of breast cancer linked to the likelihood of a cure or the risk of recurrence?
Staging breast cancer does more than just help determine treatment plans; it also aids in better understanding the prognosis. However, outcomes also depend on factors ...others, such as the specific type of breast cancer. Dr. May believes that breast cancer stages 0 through III are curable, whereas stage IV breast cancer is not—at least in principle.
However, newer treatments are helping people with metastatic breast cancer live longer. Life expectancy for those diagnosed with metastatic breast cancer can vary significantly, depending on factors such as the type of breast cancer, its response to treatment, the individual's general health, and lifestyle factors.
Staging breast cancer can also help assess the likelihood of the cancer returning after treatment. As a general rule, the more advanced the stage, the higher the risk of recurrence.
Dr. May notes that patients with stage II or III breast cancer face a higher risk of recurrence compared to those with stage 0 or stage I disease. It is also worth noting that recurrence risk is linked to the cancer subtype; for instance, triple-negative breast cancer and inflammatory breast cancer are more likely to recur than other types.
It is important to note that treatment outcomes are also influenced by the patient's adherence to their care plan. While the initial diagnosis cannot be changed, following a doctor's guidelines can impact treatment results and the risk of recurrence. This is particularly crucial when breast cancer is detected early, as most cases are curable at that stage. Although some patients do experience a recurrence, the majority show improvement during initial treatment.
March 20, 2024