Common questions about cancer recurrence

Can a person ever be sure the cancer will never come back?

No, it is not possible to guarantee that a person who has completed cancer treatment will never have the cancer come back. Even though your doctor may say, “The cancer is gone,” or “I think I removed all the cancer,” or “I see no evidence of any cancer,” the fact remains that there is always a chance that some cancer cells are left in your body and survived, even though they cannot be seen or found with any test used today. Over time, these cells can begin to grow and cause the cancer to recur.

And while you don’t want to ever think about the chance of having a second cancer – one that is not related to the first cancer – this is also possible. Having one cancer doesn’t make you immune to having a second or even a third different cancer.

Why won’t my doctor give me a “no-cancer guarantee?”

Cancer is not predictable. No doctor can guarantee cancer will stay gone forever.

A recurrent cancer starts with cancer cells that the first treatment didn’t fully remove or destroy. This does not mean that you got the wrong treatment. It does not mean that you did anything wrong after treatment, either. It means that a small number of cancer cells survived the treatment you had. There were probably too few to be detected on tests or scans. But over time, these cells grew into tumors or cancer that your doctor could finally detect as a recurrence.

Just as it happened the first time, there is also a chance that some of your normal cells may, for any number of reasons, develop damage in their DNA. (DNA holds genetic information on cell growth, division, and function.) This damage then causes a gene (a small segment of DNA) to change (mutate). When genes mutate, they can become oncogenes, which can allow cells to become cancer cells that divide too quickly and out of control.

There are also tumor suppressor genes, which tell cells when to repair damaged DNA and when to die (a normal process called apoptosis, or programmed cell death). These genes are like the brakes on a car. Just as a brake keeps a car from going too fast, a tumor suppressor gene keeps the cell from dividing too quickly. When tumor suppressor genes are mutated or turned off – that is, when the brakes fail – the cells divide very fast, allowing cancer cells to develop. Changes in tumor suppressor genes can be inherited (you are born with them), but more often they happen during your life. (See our document called Oncogenes, Tumor Suppressor Genes, and Cancer to learn more about this.)

Not all of the growth factors for cancer cells have been found yet. Even though treatment may seem to have gotten rid of all of the cancer, there may be just one tiny cancer cell left someplace in the body. This cell may be “asleep” and not cause any harm for many years. Suddenly, something can happen that will change the immune system and “wake up” the cell. When it becomes active, it can grow and make other cells. The result is a cancer recurrence.

What does “5-year survival rate” mean?

The 5-year survival rate refers to the percentage of patients who are alive at least 5 years after their cancer is diagnosed. Many of these people live much longer than 5 years after diagnosis, but the 5-year rate is used as a standard way to discuss the prognosis( survival outcome).

You may also hear the term 5-year relative survival rate. Relative survival compares survival among cancer patients to that of people not diagnosed with cancer, but of the same age, race, and sex. It is used to adjust for normal life expectancy when cancer is not present. 5-year relative survival rates are considered to be a more accurate way to describe the prognosis (long-term outlook) for groups of patients with a certain type and stage of cancer. But they cannot predict how long you or any other person may live.

If you look at these survival rates, keep in mind that 5-year rates are based on patients who were diagnosed and first treated more than 5 years ago. These statistics may no longer be accurate because improved treatments often result in better outcomes for those who were diagnosed more recently.

There is another point to remember when talking about survival rates: Survival rates look at survival only, not whether the person is cancer-free 5 years after diagnosis. They are based on a group of people of all ages and health conditions diagnosed with a certain type of cancer. These statistics include people diagnosed early and those diagnosed late. As with any statistics, they should only be used to get an idea of the overall picture. They cannot be used to predict any one person’s outcome.

Why won’t the doctor say “You are cured”?

Most doctors avoid using the word “cure” because it implies that the cancer is gone forever. As we have discussed, this is almost impossible to say in any case of cancer. The best a doctor can do is say that they can find no signs of cancer in your body at this time. This is most often stated as “No evidence of disease.” Your doctor may continue to watch you closely for many years and do tests to watch for any signs of cancer recurrence. Be aware that it is still possible for cancer to come back even after you have been cancer-free for 5 years or more.

What does it mean if the doctor says “The cancer is controlled”?

A doctor may use the term controlled if your tests or scans show that the cancer is not changing over time. Another way of defining control would be calling the disease stable. Controlled means that the tumor does not appear to be growing. Some tumors can stay the same for a long time, even without any treatment. Some stay the same size because of the cancer treatment and are watched to be sure that they don’t start growing again.

What does it mean if the doctor says “The cancer has progressed”?

If the cancer does grow, the status of your cancer changes and your doctor might say that the cancer has then progressed. Most clinical trials define a tumor as progressive when there is a 25% measured growth in the tumor. (See the section, “The difference between recurrence and progression” for more on this.)

How is the response to treatment described?

When a treatment completely gets rid of all tumors that were able to be measured or seen on a test in some way, it is called a complete response or complete remission. The decrease in tumor size must last for at least one month to count as a response. This does not mean the cancer has been cured.

In general, a partial response or partial remission means the cancer partly responded to treatment, but still has not gone away. If you are in a clinical trial this usually is defined more precisely. A partial response is most often defined as at least a 50% reduction in measurable tumor. The reduction in tumor size must last for at least 1 month to qualify as a response.

How long is treatment given before the doctor can tell if there is a response?

The first treatment given for cancer is based on the past 20 to 30 years of clinical experience in treating that kind of cancer. But no 2 cases are exactly alike, and response to treatment cannot always be predicted.

Standard practice is to wait for 2 full cycles of treatment before looking for any response to it. This usually takes about 2 to 3 months. Response is checked by repeating the tests that show the cancer. If the tumor doesn’t respond to the first treatment, changes will be made, perhaps to another chemotherapy combination that has shown promise in similar cases.