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If you have been diagnosed with breast cancer, your physician will have an in-depth discussion with you about your treatment options. Radiation therapy is one type of treatment that may be included in your treatment plan. At Yale Medicine, our radiation oncologists work with a multidisciplinary team to devise a course of treatment that is personalized to your needs. 

“Over the last decade, there have been many improvements in how Yale Medicine delivers radiation therapy for breast cancer,” says Meena Moran, MD, director of the Breast Cancer Radiotherapy Program at Yale Medicine.

What is breast cancer?

Breast cancer occurs when malignant cells form and grow in the tissues of the breast, leading to a tumor. It is the most common cancer affecting women in the United States; about 12% of women in the United States will develop breast cancer in their lifetimes. While breast cancer remains all too common, it is now being caught earlier and, as a result, it is significantly more treatable than in the past. 

What are the types of breast cancer?

Most cases of breast cancer start in the breast’s milk-producing glands, called lobules, or in the breast’s milk ducts. These types of cancers are called carcinomas. There are several subtypes of carcinomas:

Ductal carcinoma in situ (DCIS) is an early form of noninvasive cancer in which cells that normally line the duct start to grow abnormally but remain within the duct itself without invading nearby tissue. About one in five new cases of breast cancer each year are a DCIS.

Invasive ductal carcinoma, by contrast, occurs when these same cancerous cells that originally line the ducts grow abnormally and spread outside of the duct. This is the most common form of breast cancer diagnosed in the United States, accounting for about eight in 10 new cases annually.

Invasive lobular cancer (ILC) involves cancerous cells that originate in the lobules of the breast, at the end of each duct. They grow abnormally and invade surrounding breast tissue. ILC is the second most common type of invasive breast cancer in the United States.

Sarcomas occur when cancer begins outside of the lobules or the ducts, in connective tissue, muscle or nerves within the breast. These forms of breast cancer are rare and account for less than 1% of all breast cancers.

What are risk factors for breast cancer?

Factors that can increase risk of developing breast cancer include:

  • Age: This is the most significant risk factor for breast cancer. About two-thirds of breast cancer cases in the United States occur in women ages 55 and older.
  • A combination of factors: In most cases, a combination of genetic (such as a family history of the disease or having dense breast tissue), environmental and lifestyle factors (including having children later in life, being overweight and consuming alcohol) can contribute to the development of breast cancer.
  • Genetics: Only five to 10% of all breast cancer cases occur in women who are actually carrying a so-called “breast cancer gene.” In these cases, women have inherited a harmful mutation in one of two genes commonly called the breast cancer genes: BRCA1 and BRCA2 (abbreviations for breast cancer susceptibility gene 1 and breast cancer susceptibility gene 2). When functioning normally, these genes help repair damaged DNA within cells, thus helping normal cells within the body remain stable, and repair themselves without growing or reproducing abnormally. If the genes have mutated, they cannot do their job correctly and cells grow abnormally, which is what cancer is. Not everyone who has these mutations develops breast cancer, but the risk is higher. Up to 65% of women who have inherited a harmful BRCA1 mutation will develop breast cancer by the time they turn 70; whereas in women with a BRCA2 mutation, 45% will develop breast cancer by 70.

What are the symptoms of breast cancer?

The awareness of mammography for breast cancer has increased dramatically over the last several years, increasing the number of women having the screening. Thus, breast cancer is being detected at much earlier stages of the disease, often before any symptoms have developed.

For the minority of breast cancer patients who actually develop symptoms, the most common is the appearance of a new, usually painless, lump in the breast. The majority of lumps that women find in their breasts are caused by something other than cancer, such as scar tissue, cysts or a benign breast tumor; a small fraction of patients will have a lump that turns out to be cancerous, however, so any new lumps should be examined by a doctor.

Other warning signs include:

  • Unexplained swelling or shrinkage of the breast
  • Skin of the breast, the areola or nipple, becomes red, itchy, scaly, dimpled or develops a rough appearance similar to an orange skin
  • New, unexplained pain that doesn’t go away in the nipple or one area of the breast
  • Any sudden, unexpected discharge from the nipple, especially clear or bloody discharge
  • Any new retraction or inversion of the nipple
  • A lump in the armpit

Each of these symptoms, on their own or even in combination, do not necessarily mean a person has breast cancer. These symptoms are potential warning signs of several other conditions, too. For example, swelling could be a result of mastitis/cellulitis of the breast, which is an inflammation of breast tissue usually caused by an infection. Pain can occur because of a cyst, a noncancerous tumor or trauma to the breast. Nipple discharge can occur because of a hormonal problem, pregnancy or irritation within the duct. Still, the appearance of any of these should prompt a visit to a healthcare professional with expertise in breast health.

How is breast cancer diagnosed?

If a screening mammogram or a physical exam of the breast detects something abnormal, a patient may undergo further testing, including:

  • Diagnostic mammogram: More detailed than a screening mammogram, this X-ray allows the radiation oncologist to focus more closely on a potentially troublesome target area and more images are taken at various angles in order to get a more complete and detailed look at the breast tissue.
  • Ultrasound: This is another way doctors can get a more detailed picture of a breast mass or lump. The ultrasound uses harmless and painless radio waves that bounce off tissues and are converted into images on a monitor. An ultrasound is particularly useful in helping doctors to determine the size and exact location of a mass, and to distinguish a cyst (a fluid-filled sac that’s usually not cancerous) from a solid lump, which has a higher likelihood of being a cancer.
  • Magnetic Resonance Imaging (MRI): A breast MRI scan uses radio waves generated by a powerful magnet that’s linked to a computer to obtain detailed images inside the breast. Like the other imaging tests, MRI is another way doctors can assess a breast mass and allows for a more complete look both at lymph nodes affected by the breast.

If imaging scans lead doctors to believe a mass could be cancerous, the only way to know definitively is to perform a biopsy whereby a tissue sample is drawn from the mass. There are multiple biopsy techniques, but most commonly a needle is used to obtain the sample. A pathologist analyzes the sample under a microscope to determine if cancerous cells are present.

Blood tests to assess various cancer-related markers in the blood may also be ordered. These tests provide doctors with more important details about the cancer and shape treatment decisions.

What is the prognosis with a breast cancer diagnosis?

Part of the diagnostic process is determining the breast cancer’s stage, which is a number from 0 to IV that indicates how advanced the disease is. This classification is important to developing an effective treatment strategy. Typically, breast cancer is staged using a system called TNM, in which T stands for tumor size, N refers to the number of lymph nodes near the breast infected with cancer and M stands for metastases, meaning the cancer has spread outside the breast to other parts of the body.

In general, Stage 0 means that the cancer is ductal carcinoma in-situ and has remained within the ducts.

Stage I means that the tumor is very small and has not involved any lymph nodes.

Stage II indicates that the tumor is larger and/or that the cancer has traveled to the lymph nodes in the axilla, or underarm.

In Stage III, the cancer is larger and/or has spread more extensively to nearby tissues outside the breast.

And in Stage IV, the cancer has spread to other sites in the body outside the breast and the lymph nodes that are affected by the breast, such as to the lungs, liver or brain.

How is breast cancer treated with radiation therapy?

Breast cancer is typically treated by a team of doctors, consisting of surgeons, medical oncologists and radiation oncologists. Patients usually have more than one type of treatment, determined by the cancer’s stage and the patient’s overall health, age and medical history.

A treatment plan may include surgery (lumpectomy or mastectomy) to remove the tumor and affected tissue, chemotherapy to slow the tumor’s growth and/or kill cancer cells, hormone therapy and targeted therapy. Often, patients with breast cancer will also require radiation treatment to the breast, chest wall and, possibly, the lymph nodes. Radiation therapy uses high-energy radiation to damage the DNA inside cancer cells, killing the cells or preventing them from dividing and spreading.

What types of radiation therapy may be considered?

Over the past 10 years, there have been major advances in the delivery of radiation therapy, and Yale Medicine uses the latest techniques.

“We’re now able to deliver it much more safely and to confine the radiation beam to expose it only to tissue that’s at risk for returning cancer.," says Dr. Moran. "This significantly decreases exposure to normal tissues, such as of the underlying heart and lung.” Similarly, through delivery of a more consistent dose throughout the breast or chest wall, “the skin toxicity is less, so patients have fewer radiation burns during treatment, and less scar tissue after treatment,” Dr. Moran says.

A doctor may recommend the following types of radiation therapy:

  • External beam radiation.  The majority of breast cancer patients who have had breast-conserving surgery to remove a cancerous lump are treated post-surgery with external beam radiation, which is delivered from outside the body via a machine while the patient lies still on a treatment table. For patients who have had a mastectomy, radiation is also used to kill any potential cancer cells that may be present on the chest wall; it may also be used to treat some later-stage cancers that have spread, as well. An external beam radiation treatment session takes about 15 minutes, and the patient does not feel anything.
  • Hypofractionated radiotherapy. Another improvement in radiation for breast cancer involves the increased use of hypofractionation, which consists of delivering higher daily doses of radiation each session, with fewer overall sessions, thereby shortening the radiation treatment course. Using conventional radiation, a patient generally receives treatment five days a week for up to six-and-a-half weeks. With hypofractionation, “we can now complete radiation therapy in about three to four weeks, for patients who are candidates,” Dr. Moran says.

What makes Yale Medicine’s approach to treating breast cancer unique?

Breast cancer patients treated at Yale Medicine benefit from a multidisciplinary approach in which surgeons, medical oncologists and radiation oncologists work together to develop an individualized treatment plan for each patient. Treatment at Yale Medicine is data-driven, with the team taking into account the latest and best medical information available to decide what is best for the patient.

For example, Yale Medicine radiation oncologists now treat patients in various positions in order to best target a tumor. Traditionally, all patients were treated lying on their backs with their arms up. But new equipment now allows our doctors to treat patients lying on their stomachs, too. This technique allows the breast to hang forward, away from the chest wall, reducing exposure to the heart and lungs.

The team also uses another important technique: deep inspiration breath hold (DIBH), which allows the radiation oncologist to design the treatment plan where the radiation beam is only “on” after the patient takes a deep breath, which moves the chest wall away from the heart, thereby exposing less of it to radiation.

Treatment across Yale Medicine’s centers adheres to strict protocols and quality assurance checks, so that patients receive the most effective, safest care available. All patients receiving radiation for breast cancer have their treatment plans reviewed and evaluated at a weekly Breast Chart Rounds, which Dr. Moran says is just one more quality-assurance measure put in place for patients.