De novo metastatic breast cancer

Most cases of metastatic breast cancer develop from breast cancer that was treated at earlier stages. But about 6 percent of patients in the United States with newly diagnosed breast cancer have de novo metastatic breast cancer, according to the American Society of Clinical Oncology.

De novo metastatic (or stage 4) breast cancer has already spread, or metastasized, to distant parts of the body by the time of diagnosis. As breast cancer screening and treatment have improved, the rate of people diagnosed with de novo metastatic breast cancer has declined.

Causes

Cancer forms when a cell begins dividing uncontrollably, usually as a result of a gene mutation. The exact cause of cancer isn’t always clear.

Certain risk factors increase someone’s chance of developing cancer. However, cancer may occur in people with and without risk factors.

In general, the risk factors for de novo metastatic breast cancer are the same as those for developing any stage of breast cancer.

Risk factors that can’t be controlled include:

• Being female, age 55 or older, white or taller than average
• Having a family or personal history of breast cancer
• Having certain noncancerous breast conditions, such as atypical ductal hyperplasia or lobular carcinoma in situ
• Inheriting certain gene mutations—according to the American Cancer Society, about 10 percent of breast cancers are inherited
• Having dense breast tissue 
• Having started menstruation before age 12

Other risk factors are related to lifestyle factors, such as:

• Drinking alcohol
• Being overweight or obese
• Taking estrogen (such as for menopause hormone therapy or birth control)
• Not having children
• Not breastfeeding

Some risk factors for de novo metastatic breast cancer are related to social determinants of health, which may impact access to care or delay care. These risk factors include:

• Living in a rural environment
• Being unemployed
• Being nonwhite (with the exception of Asian races)
• Denying having a disease
• Having lower socioeconomic status

Though it’s unclear exactly what causes metastatic breast cancer, undergoing regular mammograms increases the chances of catching breast cancer at an earlier, more treatable stage.

Symptoms

In metastatic breast cancer, the cancer has spread to areas of the body beyond the breasts. Though the tumors are in different organs or tissues, the cancer is still considered breast cancer.

De novo metastatic breast cancer most commonly spreads to the bones, liver and lungs, but it may also spread to the brain or other organs.

General symptoms of metastatic breast cancer include:

• Fatigue
• Loss of appetite
• Vomiting
• Weight loss

Other symptoms depend on where the cancer has spread. For example:

• Cancer that has spread to the bones may cause bone fractures; pain in the back, neck or other bones or swelling.
• Cancer that has spread to the liver may cause yellowing of the skin or whites of the eyes, itchy skin rashes, nausea or pain or swelling in the belly.
• Cancer that has spread to the lungs may cause shortness of breath, difficulty breathing or chronic coughing.
• Cancer that has spread to the brain may cause personality changes, blurry vision, headaches, seizures, confusion or loss of balance.

Treatment

Metastatic breast cancer treatment strategies focus on extending quality of life and managing disease. Just as cancer is specific to each patient, cancer treatment is also tailored to each patient’s disease. Lab tests identify the cancer’s characteristics (like its hormone receptor status or whether it has certain gene mutations) to determine which therapies may be appropriate.

Treatment for de novo metastatic breast is similar to treatment for regular metastatic breast cancer, which includes hormone therapy, chemotherapy, targeted therapy, immunotherapy, radiation therapy, surgery and palliative care.

Treatment plans may include one or more systemic drug therapies to shrink the tumor by killing cancer cells, including those below.

• Hormone therapy, considered the frontline treatment, uses specific hormone receptors to target and destroy cancer cells.
• If hormone therapy doesn’t work, doctors may suggest chemotherapy, which kills rapidly dividing cancer cells.
• Targeted drug therapy treats cancer with specific genetic mutations.
• Immunotherapy empowers the immune system to attack the cancer cells.

Occasionally, treatment plans may include radiation therapy or surgery to manage symptoms in areas where the cancer has spread.

Palliative care is also an important part of treating de novo metastatic breast cancer. Through palliative care, patients may receive medications to control the side effects of cancer drugs and psychological support as part of their treatment plans. Treatments vary depending on where the cancer has spread.

Prognosis and survival rate

De novo metastatic breast cancer is stage 4 cancer, which accounts for the majority of breast cancer deaths, according to the American Society of Clinical Oncology. Its prognosis is better than that of patients with recurrent metastatic breast cancer and short intervals with no evidence of disease (for breast cancer that has undergone previous treatment). However, advanced age has been linked to a worse prognosis.

Based on a 2020 study in BMC Cancer that used data from the National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) program, the survival rate of patients diagnosed with de novo metastatic breast cancer was 74.5 percent after one year and 45.3 percent after three years. The five-year survival rate was 28.2 percent. This five-year rate is similar to the overall five-year survival rate for metastatic breast cancer, which is 29 percent for females and 22 percent for males, according to the American Society of Clinical Oncology.