As number of cancer survivors grows, so does rate of second malignancies

There are approximately 14.5 million cancer survivors in the United States, according to the American Cancer Society.

That number is expected to climb to nearly 19 million by 2024, the society estimates.

Eric Horwitz

Although advances in early detection and treatment have dramatically increased the likelihood that Americans will survive their initial cancer diagnosis, the fact they are living longer — coupled with after-effects of radiation and other therapies — makes it more likely they may develop a second type of cancer later in life.

HemOnc Today spoke with Eric Horwitz, MD, chairman of the department of radiation oncology at Fox Chase Cancer Center — Temple Health in Philadelphia, about the increasing incidence of second cancers, whether certain patient populations are at increased risk and what priorities should be established for future research into second malignancies.

Question: What are the most recent statistics for the rate of second cancers in the United States?

Answer: Roughly 1% to 3% of people who have had one cancer go on to develop a completely new cancer down the road. However, this is a number that needs to be taken with a grain of salt, as the rate is actually quite low.

Q: Are there certain cancer types that are more prevalent than others?

A: The types of second cancers that are more prominent are actually the cancer types that are most common to start with. These include prostate cancer, lung cancer and colorectal cancer in men, and breast cancer, lung cancer and colorectal cancer in women.

Q: Is there a certain population that seems to be affected by second cancers more than others?

A: Not necessarily. There is a suggestion that if you have had one cancer, there is a slight risk for the development of a second cancer that is completely different from the first cancer and has nothing to do with that first diagnosis. The one group that is at higher risk for developing a second cancer is the pediatric cancer population. People who were treated for a cancer when they were children have higher rates of second cancers compared with the adult cancer population.

Q: If patients are scared that they will develop a second cancer — or are concerned that a treatment modality such as radiation may increase their risk for a second malignancy — what advice do you give them?

A: I tell my patients that they need to receive the best treatment possible that will give them the best chance to cure their cancer. The risk for developing a second cancer is extremely low from the treatment itself, far lower than the risk of recurrence if their cancer is not adequately treated. Patients who are treated for cancer are typically followed more closely than the general population so that if they develop another cancer, it is possible that it will be discovered earlier.

Q: In your opinion, why do second cancers occur?

A: Two reasons. First, it is the risk factors associated with cancers. One major factor for cancer development is smoking. If a person smokes and they had a head and neck cancer, the risk for the patient to get another cancer caused by smoking is pretty high. Another example is that people do not always appreciate that bladder cancer is associated with smoking, so if someone is diagnosed with lung cancer from smoking, they are susceptible to bladder cancer also from smoking. A second reason is that the treatment for cancer has advanced and become a lot better, so more people are cured of their first cancer and are living longer. They subsequently have a risk for getting another cancer because they are alive. Not as many people are dying of that first cancer, so there is more of a risk for something else to happen. One could look at this as the glass “half empty” or “half full.” I prefer to look at it as a glass half full.

Q: What, if anything, can be done to prevent or reduce the risk for a second cancer?

A: I would say the same general things that we all know to be true — a healthy diet, exercise and appropriate screening. Yet another reason why we are finding these second cancers is that people who have been treated for one cancer tend to have good follow-up and tend to be watched carefully and closely, so these second cancers are being detected during follow-up. Using colorectal cancer as an example, patients should undergo colonoscopies at the appropriate interval. For breast cancer, we have mammography, and for prostate cancer, we have PSA testing.

Q: What should future research into second cancers entail?

A: We need to continue to investigate and better understand the genetic and environmental basis for cancer development. Another area of research, which is especially relevant to me as a radiation oncologist, is how does a person’s original cancer treatment impact the treatment for a second cancer? There is a common belief that a patient who has had radiation due to a previous cancer cannot get radiation again. This is not a completely true statement. This would only apply when giving a patient radiation to the exact same area as before — and, even in this situation, there are times when we can re-irradiate. A patient can safely receive radiation to a different body part or area. For example, if a patient received radiation for prostate cancer and now they have lung cancer, they can receive whatever radiation treatment is appropriate and necessary for their lung cancer. However, if the person’s second cancer is close to where the original cancer was located, then this can impact how people are treated. Clearly, doing more research that looks into how to treat a patient who has already been treated once for cancer is important. – by Jennifer Southall

For more information:

Eric Horwitz, MD, can be reached at Fox Chase Cancer Center, 333 Cottman Ave., Philadelphia, PA 19111; email: eric.horwitz@fccc.edu.

Disclosure: Horwitz reports no relevant financial disclosures.