A New Primary Cancer vs. A Recurrence

If you have had cancer before and something new turns up — a lump, a spot on a scan, a symptom that will not settle — one of the first things your team has to sort out is whether this is your old cancer returning or a completely different cancer that started on its own. These are two different situations with two different names, and the answer shapes what treatment you are offered.

Recurrence. When cancer comes back after treatment, doctors call it a recurrence or recurrent cancer. Recurrent cancer starts with cancer cells that the first treatment did not fully remove or destroy. A small number of cells survived, stayed too small to show up on any scan, and over time grew into a tumor that can now be seen.

A second primary cancer. Sometimes a new type of cancer occurs in a person who has a history of cancer. That new cancer is called a second primary cancer, and the National Cancer Institute is explicit that it is different from recurrent cancer. It did not grow from the first cancer. It began separately.

Cancer keeps the name of the place it started. When cancer spreads, it is still the same type of cancer. So breast cancer that returns in the lung is still breast cancer, and it is treated with breast cancer treatments. A second primary lung cancer in someone who once had breast cancer is a true lung cancer and is treated as lung cancer. Same location on the scan, different disease, different drugs.

• Local recurrence — the cancer is in the same place as the original cancer or very close to it.
• Regional recurrence — the tumor has grown into lymph nodes or tissues near the original cancer.
• Distant recurrence — the cancer has spread to organs or tissues far from the original cancer. This is also called metastatic cancer.

For breast cancer, NCI describes local recurrence as cancer returning in the same area where the first tumor was found, or in the chest wall or surgical site after a mastectomy. Regional recurrence appears in lymph nodes under the arm, in the collarbone area, or in the neck. Distant recurrence most often shows up in the bones, lungs, brain, or liver.

To figure out the type of recurrence you have, you will have many of the same tests you had when your cancer was first diagnosed, such as lab tests and imaging procedures. For breast cancer specifically, NCI says the tests used are the same ones used to make your original diagnosis. This is why the answer often takes more than one appointment: the imaging shows where the abnormality is, and the tissue and lab work help show what it is.

Nearly one in five cancers diagnosed today occurs in someone with a previous diagnosis of cancer. The number of cancer survivors in the United States has grown from about 3.5 million in the 1970s to more than 17 million, and second cancers are a leading cause of illness and death in that group. Radiation therapy and certain chemotherapies may raise the risk of developing a second cancer, and some inherited conditions — such as ataxia telangiectasia — make people more sensitive to radiation's cancer-causing effects. Researchers are also studying obesity and tobacco as contributors.

This is one reason survivorship follow-up continues long after treatment ends.

NCI lists these as possible signs of returning breast cancer, and they give a sense of what is worth mentioning promptly: a new lump, a change in breast size, dimpling or redness of the skin, a nipple turning inward, or swollen lymph nodes. Signs that can point to distant spread include persistent bone or chest pain, neurologic changes, trouble breathing, a cough that does not go away, yellowing of the skin or eyes, and unexplained weight loss.

Treatment may involve chemotherapy, surgery, radiation, biological therapies, or a combination of treatments. Clinical trials may also be an option worth asking about.

Finding out that cancer has come back can cause feelings of shock, anger, sadness, and fear. NCI also points out something true and useful: you are not starting from zero this time. You have been through the system before, you know your own body and your own preferences, and you can take an active part in the decisions ahead.

• Is this a recurrence of my original cancer or a new primary cancer?
• Which tests will answer that, and when will the results be back?
• If it is a recurrence, is it local, regional, or distant?
• Could my earlier radiation or chemotherapy have played a role?
• What treatment options does this specific answer open up, and are there clinical trials?

• National Cancer Institute — Recurrent Cancer: https://www.cancer.gov/types/recurrent-cancer
• National Cancer Institute — Recurrent Breast Cancer: https://www.cancer.gov/types/breast/breast-cancer-survivorship/recurrence
• NCI Division of Cancer Epidemiology & Genetics — Second Primary Cancers Among Cancer Survivors: https://dceg.cancer.gov/research/what-we-study/second-cancers

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