A New Primary Cancer vs. A Recurrence

You have had cancer before, and now something new has turned 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 which of two things this is. Is it your old cancer returning? Or is it a completely different cancer that started on its own? These are two different situations with two different names. 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. They stayed too small to show up on any scan. Over time they 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. 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. 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 it is treated as lung cancer. Same location on the scan, and a different disease.

Origin sets the starting point rather than settling the answer. What the cells look like under the microscope, the biomarker results, where the disease is and how much of it there is, what treatment you had before and how long ago, your other health and what you want from treatment all shape what is actually offered.

Sorting a recurrence from a second primary is not always clean either. Pathologists compare the appearance of the two tumours and may compare their molecular profiles. Sometimes the answer is clear. Sometimes it stays uncertain, and the team plans around that uncertainty rather than pretending it away.

• 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. It can also appear 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 find out which 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. 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. The tissue and lab work help show what it is.

A large share of new cancer diagnoses occur in people with a previous diagnosis. NCI planning material has put the figure near one in five; that estimate dates, and it is worth checking against current surveillance data before quoting it. The direction is not in doubt. The number of cancer survivors in the United States has grown from about 3.5 million in the 1970s to more than 17 million. 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. 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 a set of changes that can signal breast cancer coming back. Some point to disease near where it started. Others point to spread further away. They do not all carry the same urgency, so here they are sorted by how fast to act.

• Call 911 or go to an emergency department if you suddenly cannot get your breath, or a neurologic change arrives abruptly — one-sided weakness, a first seizure, slurred speech, or confusion that was not there an hour ago.
• Call 911 or go to an emergency department if back pain comes with new leg weakness or numbness, or you lose control of your bladder or bowels, or cannot empty your bladder. Pressure on the spinal cord can cause lasting paralysis within hours, so this cannot wait for a clinic call.
• Call 911 or go to an emergency department if severe chest pain sets in. Do not wait for a clinic callback to find out whether it is the cancer, the heart or the lungs.
• Call your care team the same day if the whites of your eyes or your skin turn yellow, or bone pain becomes severe.
• Call your care team within a day or two if you find a new lump, notice a change in breast size, skin dimpling or redness, or a nipple that has turned inward; or if you have swollen lymph nodes, a cough that will not clear, or weight loss you cannot account for.

If you are between scans and unsure whether something counts, report it anyway and let the team decide.

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 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