Many people are confused about the definitions of primary, secondary, or secondary cancer. Primary cancer is defined as the original site (organ or tissue) where the cancer started. In contrast, a secondary or secondary cancer can be defined in a number of ways; either as a new primary cancer in another area of the body or as metastasis (spread) of the original primary cancer to another area of the body.
For example, cancer that starts in the lungs is called primary cancer.lung cancer. When lung cancer spreads to the brain, it is called primary lung cancer.metastaticto the brain or secondary brain tumor. In this case, the cancer cells in the brain would be lung cancer cells, not brain cancer cells. Conversely, a person can have one primary lung cancer and an unrelated second primary brain tumor. In this case, the cancer cells in the brain would be brain cells and not lung cells.
As mentioned above, primary cancer refers to the initial cancer that a person develops, whether it is lung cancer, breast cancer, or some other type of cancer. It is possible to have more than one primary cancer; Sometimes these primary cancers are found at the same time, and sometimes they occur decades apart (see below). This is not surprising since some cancer risk factors, such as smoking, increase the risk of various types of cancer. There are also a number of hereditary cancer syndromes that increase the risk of cancer in more than one type of organ or tissue.
Second primary vs. secondary cancer
The terms secondary and second cancer are sometimes used interchangeably but can have different meanings. The term secondary cancer can refer to metastasis from the primary cancer or to a second cancer unrelated to the original cancer. When the term secondary cancer is used, it generally refers to a second primary cancer, in other words, a different cancer than the first, arising in a different organ or tissue.
Second primary cancers
Secondary primary cancers are not directly related to the primary cancer because each of these cancers arises from mutations that occur in different cells. That being said, secondary primary cancers are more common in people who have had a primary cancer than in people who have not had cancer, for a variety of reasons. These include:
- Similar risk factors: Some cancer risk factors increase the risk of several types of cancer.For example, smoking is linked to several types of cancer. There are also different types of cancer that are linked to excessive alcohol consumption, and so on.
- Hereditary predisposition: Some people inherit a predisposition to cancer, which can increase their risk of developing several different types of cancer.For example, mutations inTumorsuppressorgeneifThe BRCA2 gene mutation, increase the risk not only of breast cancer but also of ovarian cancer, prostate cancer, leukemia, pancreatic cancer and lung cancer in female smokers.
- Treatment-related cancers: Cancer treatments, like many chemotherapy drugs and radiation therapy, can increase your risk of developing another cancer in the future.. For example, one of the commonly used chemotherapy drugs for breast cancer can increase your risk of developing leukemia. Second primary cancer as one of the possibleLong-term side effects of cancer treatmentIt is an active area of research with studies looking at radiotherapy options as well as chemotherapy drugs that are less likely to cause a second primary cancer.
As people with cancer survive longer, the incidence of secondary primary cancers is expected to increase and is already significant. A 2017 Israeli study found that 3.6% of breast cancer survivors developed a second primary cancer within 5 years of their original diagnosis and 8.2% within 10 years of their diagnosis.Another way to understand the seriousness of the problem is to look at the impact of secondary primary cancers on people who have had cancer. Currently, secondary primary tumors are the second leading cause of death (after the original cancer) in people with head and neck cancer.
In Hodgkin's disease, treatment of the disease, often undertaken at a young age, is associated with a high survival rate and a high risk of secondary cancers. The risk is estimated at 20 to 30 percent.For this reason, screening tests such as MRIs for breast cancer are often recommended (rather than mammograms, which can miss up to 15 percent of breast cancer cases).
Secondary cancer in Hodgkin lymphoma survivors
cancer of unknown origin
In some cases, the original site at which a cancer begins is unknown, and doctors may not be sure whether the cancer diagnosed is secondary (metastatic) to a cancer that has not yet been found or is a primary cancer. . In 3 out of 100 cancer patients, the primary site of the cancer is not found. If this is the case, the tumor is generally referred to as metastatic cancer of unknown primary origin.
With better diagnostic tests and molecular profiling, the diagnosis of cancer of unknown cause is less common than in the past, but it still happens. The reason is often that a tumor is very "undifferentiated".Cancer cells can look like normal cells, sometimes making them relatively indistinguishable under the microscope. Even if a primary site for a cancer cannot be determined, doctors can still treat that cancer.
Cancer doesn't always have a primary location. An example of this is lymphoma. Although the primary site at which lymphoma begins may not be known, it is not considered a cancer of unknown origin. Tumors like this can be confusing when it comes to primary and secondary cancers, since lymphomas can be found in many tissues. In this case, however, all the cells under the microscope would be lymphoma cells. So if the gastric cancer cells were lymphoma cells they would be part of the primary cancer, but if they were gastric cells they would be considered a secondary cancer. . . primary cancer.
A word from Verywell
Cancer-related terminology can be confusing, especially when a person develops more than one type of cancer or has metastatic disease. At the same time, we know that being your own advocate in your care is very important, and understanding your condition is essential to that. Take the time to learn more about your cancer. ask lots of questions If the answers are still not clear, ask again. And don't hesitate to get a second opinion before making any decisions. Distinguishing between primary and secondary cancer can make a significant difference in treatment options and approaches.
Verywell Health uses only quality sources, including peer-reviewed studies, to back up the facts in our articles. read ourspublishing processto learn more about how we review our content and keep it accurate, reliable, and trustworthy.
Utada M., Ohno Y., Hori M., Soda M.Incidence of multiple primary tumors and interval between first and second primary tumor.cancer science. 2014;105(7):890–896. doi:10.1111/ca.12433
Ye Y, Neil AL, Wills KE, Venn AJ.Temporal trends in risk of developing multiple primary cancers: a systematic review..BMC-Krebs. 2016;16(1):849. doi:10.1186/s12885-016-2876-y
Silverman BG, Lipshitz I, Keinan-Boker L.Second primary cancers after primary breast cancer diagnosis in Israeli women, 1992 to 2006.J Glob Oncol. 2017;3(2):135-142. doi:10.1200/jgo.2016.003699
Schaapveld M, Alemán BM, Van Eggermond AM, et al.Second cancer risk up to 40 years after treatment for Hodgkin lymphoma.N English J Med. 2015;373(26):2499-511. doi:10.1056/NEJMoa1505949
American Cancer Society.What is cancer of unknown primary?
American Society for Clinical Oncology. Cancer.Net.unknown primary.
National Cancer Institute. Department of Cancer Epidemiology and Genetics.Second primary cancers.(Video) Difference between Primary and Metastatic Cancer | Central Principles of Molecular Biology
VonDra. Lynne Eldridge
Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of Avoiding Cancer One Day at a Time.
See Our Editorial Process
Meet our panel of medical experts
Was this page helpful
Thank you for your comments!
What is your opinion?
How do you know if cancer is primary or secondary? ›
To diagnose secondary cancer, a specialist doctor called a pathologist examines the cancer cells under a microscope. The pathologist can see that the cancer cells do not belong to or originate in the surrounding tissue, and this can be confirmed by further laboratory tests.Does secondary cancer mean terminal? ›
Secondary cancer can't usually be cured. But treatment can control it for some time and help prevent problems developing. Some people may not be able to have treatment for their cancer because they are too unwell.What is considered a primary cancer? ›
A term used to describe the original, or first, tumor in the body. Cancer cells from a primary tumor may spread to other parts of the body and form new, or secondary, tumors. This is called metastasis. These secondary tumors are the same type of cancer as the primary tumor.What are primary and secondary cancer examples? ›
Secondary cancers are the same type of cancer as the original (primary) cancer. For example, cancer cells may spread from the breast (primary cancer) to form new tumors in the lung (secondary cancer). The cancer cells in the lung are just like the ones in the breast. Also called secondary tumor.What is the most common secondary cancer? ›
Which secondary cancers are the most commonly diagnosed? Livingston: Leukemias, lymphomas and sarcomas. But there are others, such as breast cancer, lung cancer, and thyroid cancer, too.Is secondary cancer always stage 4? ›
stage 4 – the cancer has spread from where it started to at least 1 other body organ, also known as "secondary" or "metastatic" cancer.Can chemo get rid of secondary cancer? ›
Chemotherapy for secondary breast cancer can relieve symptoms. It can also control the cancer and improve your quality of life for a time, but it can't cure the disease. For some people treatment can control the cancer for many months or years.Can you live a long life with secondary cancer? ›
In the past, many people did not live long with metastatic cancer. Even with today's better treatments, recovery is not always possible. But doctors can often treat cancer even if they cannot cure it. A good quality of life is possible for months or even years.Can secondary cancer ever be cured? ›
In a small number of situations, treatment can cure secondary cancer. However, usually secondary cancers are not curable and the aim of treatment is to control the cancer or manage any symptoms. Depending on the type of cancer, some people will have treatments that control the cancer for several years.Can a primary cancer disappear? ›
It may be too small to be picked up on scans or be hidden beside a larger secondary cancer. It might have disappeared, even though it has spread to other parts of the body. This can sometimes happen if the body's immune system has successfully got rid of it.
What are the most common primary cancers? ›
The most common type of cancer on the list is breast cancer, with 290,560 new cases expected in the United States in 2022. The next most common cancers are prostate cancer and lung cancer. Because colon and rectal cancers are often referred to as "colorectal cancers," these two cancer types are combined for the list.Can primary cancer be treated? ›
There is no standard treatment for carcinoma of unknown primary that is found in several different areas of the body. Treatment may include the following: Hormone therapy. Internal radiation therapy.What are the signs of secondary cancer? ›
- A change in the colour of the skin.
- A persistent rash.
- A firm, painless small lump (nodule) or multiple lumps of different sizes.
- Lymphoedema (swelling of the arm, hand or breast area)
One to three percent of survivors develop a second cancer different from the originally treated cancer. The level of risk is small, and greater numbers of survivors are living longer due to improvements in treatment. However, even thinking about the possibility of having a second cancer can be stressful.Is breast cancer primary or secondary? ›
Secondary breast cancer is breast cancer that has spread from the breast to other parts of the body. Breast cancer starts as a lump in the breast - this is primary breast cancer. In many women, primary breast cancer does not come back after treatment.What drugs cause secondary cancer? ›
Chemotherapy agents that have an increased risk for second cancers include: Alkylating agents (mechlorethamine, chlorambucil, cyclophosphamide, melphalan, lomustine, carmustine, busulfan) Platinum-based drugs (cisplatin, carboplatin)How long do you live when cancer spreads to lymph nodes? ›
A patient with widespread metastasis or with metastasis to the lymph nodes has a life expectancy of less than six weeks. A patient with metastasis to the brain has a more variable life expectancy (one to 16 months) depending on the number and location of lesions and the specifics of treatment.What stage of cancer is terminal? ›
Stage 4 is the most severe stage of cancer, with the highest risk of mortality. However, many factors affect a person's life expectancy. In this article, we describe what stage 4 cancer is and the survival rates for people with different types of cancer at this stage.Can secondary cancer in lymph nodes be cured? ›
Secondary breast cancer means that a breast cancer has spread to another part of the body. This includes the liver, lungs, brain, or bones. It doesn't include breast cancers that are affecting the lymph glands under the arm. Unfortunately, secondary breast cancer can't be cured.Can a blood test detect secondary cancer? ›
Tumour marker blood test
Doctors may use the CA 15-3, along with other tests, to check if treatment is working. A raised level may suggest that the cancer is spreading in some people with secondary breast cancer. This is because other non cancerous conditions can also cause the levels to rise.
What determines what stage of cancer you have? ›
The clinical stage is an estimate of the extent of the cancer based on results of physical exams, imaging tests (x-rays, CT scans, etc.), endoscopy exams, and any biopsies that are done before treatment starts. For some cancers, the results of other tests, such as blood tests, are also used in clinical staging.Which cancers are most likely to recur? ›
Some cancers are difficult to treat and have high rates of recurrence. Glioblastoma, for example, recurs in nearly all patients, despite treatment. The rate of recurrence among patients with ovarian cancer is also high at 85%.What is the best cancer to be diagnosed with? ›
1. Breast cancer. The 5-year relative survival rate for stage 0 and 1 breast cancer is 99–100 percent . Therefore, people with this stage and type of cancer are almost 100 percent as likely to survive for at least 5 years as people without the condition.Do oncologists lie about prognosis? ›
Yet, oncologists do not routinely share prognoses. In a study of nearly 600 patients with advanced cancer, only 17.6% of the 71% who wanted to know their prognosis reported being told .What bloodwork shows cancer? ›
Circulating tumor cell tests detect cancer cells in your blood. The cells might be in the blood if they've broken away from where they started and are spreading to other parts of the body. Circulating tumor cell tests are mostly used after a cancer diagnosis.Are metastatic cancers rarely fatal? ›
In most cases, metastatic cancer is not curable. However, treatment can slow growth and ease many of the associated symptoms. It's possible to live for several years with some types of cancer, even after it has metastasized. Some types of metastatic cancer are potentially curable, including melanoma and colon cancer.What is the new test for cancer? ›
GRAIL's Galleri test, named one of Time magazine's best inventions of 2022 and a breakthrough of the year from The Atlantic, is a multi-cancer early detection (MCED) blood test to spot early signals in the blood that are associated with many cancers.Do cancer markers always show up in bloodwork? ›
It also does not help find a recurrence. Some cancers do not make tumor markers that are found in the blood. And, some types of cancer have no known tumor markers. Your tumor marker levels might not go up, even if your type of cancer usually makes tumor markers.At what stage does cancer become untreatable? ›
Stage 4 cancer usually can't be cured. In addition, because it's usually spread throughout the body by the time it's diagnosed, it is unlikely the cancer can be completely removed. The goal of treatment is to prolong survival and improve your quality of life.When is cancer considered terminal? ›
Cancer that cannot be cured and leads to death. Also called end-stage cancer.
Does cancer spread faster after biopsy? ›
A long-held belief by a number of patients and even some physicians has been that a biopsy can cause some cancer cells to spread. While there have been a few case reports that suggest this can happen — but very rarely — there is no need for patients to be concerned about biopsies, says Dr. Wallace.