Second Cancers Resulting From Chemotherapy or Radiation Treatment
Many people don't realize that they could be at risk for getting another cancer after having been successfully treated for the first one. This risk is low, however. One study reported that a high percentage of cancer survivors do not develop second cancers. The risk is real, however, and there are ways to reduce your risk.
Recurrence vs. Second Cancers
Some people confuse second cancers with recurrences.
A recurrence is the same cancer that has redeveloped or spread (also called a metastases). A recurrence was never cured; it was still there and it re-occurred. A second cancer is a completely different tumor. It would be like if you had breast cancer and you developed leukemia.
There are many reasons that someone who has already had cancer may go on to develop another type of cancer. They include: treatment from the first cancer; genetic changes, whether inherited or not; and exposure to things that can cause cancer, such as smoking. Survivors of childhood cancers and people who have undergone bone marrow and stem cell transplants also have an increased risk of developing a second cancer.
Gary Johnson (not his real name) is an example of someone who had chemotherapy and a bone marrow transplant for a previous cancer, who is now at risk for developing a second cancer. Gary, a Boston-area web developer, successfully battled Hodgkin's disease more than 10 years ago. Just recently, his doctor told him he had myelodysplasia (MDS), a serious blood disorder that can develop into leukemia.
"My doctors think that the chemotherapy and/or the bone marrow transplant that I went through for Hodgkin's disease caused my myelodysplasia," said Gary. "My doctors also discovered that my seventh chromosome in my malignant cells were getting destroyed, a condition called 'deletion of sevens.' This condition, along with myelodysplasia, means that my disease will progress aggressively."
Even if Gary's myelodysplasia does not develop into leukemia, it is serious in its own right. Luckily, doctors caught Gary's condition early and are recommending that he have a bone marrow transplant. Gary has since found a bone marrow donor that his doctors are calling "a perfect match."
Second Cancer as a Side Effect
Chemotherapy and radiation have helped many people survive cancer. These treatments can include strong medicines and strong doses of radiation. In rare cases, they can also cause second cancers. As more people survive their cancers, we will learn more about the long term and late effects of their cancer and its treatment.
Developing a second cancer due to cancer treatment can depend on many factors. It can depend on the type of cancer and treatment you had, and, in some cases, your age when you were treated for cancer. Common first cancers that can develop second cancers due to chemotherapy, radiation or a combination of both, include soft-tissue sarcomas, Hodgkin's disease, non-Hodgkin's disease, testicular cancer, breast cancer, ovarian cancer, and childhood cancers.
Chemotherapy can cause leukemia and solid tumor second cancers. Generally, blood-related cancers can develop as second cancers the first few years after chemotherapy for the first cancer ends. Solid tumors can develop as second cancers 10 to 30 years after chemotherapy treatment ends.
Radiation is mainly responsible for solid tumor second cancers, especially in bones and soft tissues in the area treated. Generally, solid tumors can develop as second cancers up to 20 years after radiation treatment for the first cancer ends.
Cancer Screenings Are Important
It's important to remember that once you've had cancer to talk to your doctor about what type of follow-up screenings and guidelines are best for you. Although Gary did not think that there was a possibility that he would develop a second cancer, his doctor kept an eye on him, just in case.
"I, very fortunately, had a primary care physician (who's not a cancer specialist), who knew what to look for," said Gary. "He always had a very low threshold for anything unusual with me. He always encouraged me to see my oncologist if he ever thought anything was wrong."
Gary regularly saw his doctor, and recent blood tests showed that he had nucleated red blood cells in his blood, which concerned his doctor. This is because normal red blood cells lose their nucleus before entering the bloodstream. Gary's doctor ordered a bone marrow biopsy to determine if anything was wrong and discovered the myelodysplasia.
Many doctors recommend regular, life-long screenings and self-exams for people with a history of cancer. Gary agrees.
"One thing people can do is to be regularly checked by their doctors, even if they are many years in remission, or are considered 'cured' from cancer," he said. "I don't think you can ever be too prudent. Go in and get checked."
Second Cancer Worries
The benefits of cancer treatment far outweigh the real, but small, risk of developing another cancer. Therefore, it's important not to let worries of developing a second cancer from treatment cause you to stop treatment for your initial cancer.
If another cancer does develop later, it will be treated based on the available treatments at that time. It is important to talk with your doctor about other treatments to see if there are options to lower the risk of getting a second cancer.
For example, someone with breast cancer may be able to choose between surgery versus breast conserving surgery and radiation. In this case, the patient should ask questions about the long term and late effects of each treatment compared to chance of being cured. Either treatment could involve risks, but the patient has options. Children's cancers, for example, may have different treatment options.
Women who had chest irradiation as children and adolescents are at risk of developing breast cancer later in life.
Because survivors of childhood cancers have so many years ahead of them, they need to be educated on the importance of healthy lifestyles and to have regular and ongoing cancer screenings.
Advances in medicine and research are improving chemotherapy and radiation treatments. It is hoped that these advances and improvements can help lower the number of treatment-related second cancers, as well as increase the chance of curing the cancer while lowering the side effects of the treatment. Researchers are finding out which chemotherapy drugs can cause second cancers. They are also discovering new ways to deliver radiation therapy.
"During those 10 years when I was 'well,' they've been able to develop other (cancer) treatments that are less noxious," Gary said. "Chemotherapy is less severe (today), and the type of bone marrow transplant I'm supposed to have is going to be less damaging to my body."
In addition, researchers are exploring new treatments for cancer, some of which are still experimental, in hopes of finding better and safer cancer treatments. For example, forms of biological therapy fight cancer using the body's immune system. Gene therapy fights cancer by changing the genetic makeup of cells. Anti-angiogenesis compounds can shrink tumors by stopping new blood vessels from growing. It will take time and experience to understand what their long term or late effects will be and whether second cancers are one of them.
While you can't completely control your risk of developing a second cancer, you can do some things to lower your risk of developing one. Lifestyle risks such as smoking, diet, and exercise can be easier to control than an x-ray or a type of chemotherapy. Studies have proved that smoking and heavy alcohol use can cause cancer. Research shows that improving your diet, exercising, and protecting yourself from sun exposure or from contracting the sexually transmitted disease, human papillomavirus (HPV), can help reduce your risk of cancer.
Cancer survivors may also want to find out about and participate in research studies about long term and later effects of cancer and its treatment. Ask your doctor or nurse for more information on these studies.