Why Do I Need Chemo if I’m Cancer-Free?
by Richard C. Frank, MD
No one really wants to meet with an oncologist if they don’t have to. People who undergo cancer surgery, of course, hope that the surgeon will come to their bedside after the operation and say, “Well, that’s it. I got everything; you’re cured. Go on with the rest of your life. This cancer won’t be bothering you again.” In reality, many people will hear something like this: “The surgery went very well. I got all the cancer. But you should meet with an oncologist in case you need chemotherapy.” All told, nearly a third of people with cancer undergo cancer treatment after surgery, called adjuvant therapy, as part of a plan to cure their cancer.
Adjuvant therapy may consist of drug and/or radiation treatments. Radiation is given to the region from which a cancer was removed in order to decrease the chances that the cancer will return there; examples include breast radiation after lumpectomy, lung radiation after removal of a lung tumor, and brain radiation after resection of a brain tumor. In contrast, drug therapies attack cancer cells wherever they may be in the body in an effort to prevent isolated pockets of cells from developing into detectable metastases.
Many people wonder why they should subject themselves to the side effects of drugs and radiation if the surgeon told them that the cancer was completely removed. The reason is that having a primary cancer removed is not always the same as being rendered “cancer-free.” The surgeon removed only the cancer that he or she could see. In many cancers, however, small clusters of cells escape into the blood or lymphatic system before the cancer is diagnosed and removed. These microscopic deposits of cancer, called occult metastases or micrometastases, cannot be detected reliably by current methods and can eventually grow to form detectable or visible tumors in the liver, lungs, bones, and other regions of the body.
Adjuvant therapy is often successful because it is easier to eradicate micrometastases than it is to eliminate overt metastases. In other words, the same type of cancer treated with the same drugs can be cured more often when metastases are microscopic than when they have become obvious and measurable. The reasons for this are not known with certainty but have to do with how much more efficiently cancer therapies penetrate small tumors and the greater likelihood of drug resistance as a cancer enlarges.
Having a primary cancer removed is not always the same as being rendered “cancer-free.”
For example, when chemotherapy is used to treat people with stage IV lung cancer, it leads to a modest improvement in survival, and cures occur only in a small percentage of cases. But when the same chemotherapy (vinorelbine and cisplatin) was recently used in a study of people with early-stage lung cancer, who are at risk to develop metastases, 69 percent of those treated with chemotherapy were alive at five years, compared to 54 percent of those who received no chemotherapy after surgical removal of the cancer. Overall, chemotherapy decreased the risk of death by more than 30 percent. What this information means is that for a number of people in whom lung cancer was destined to return and take their lives, chemotherapy (and radiation in some cases) made all the difference and stopped this process in its tracks.
An equally dramatic advance was reported in 2005 for the adjuvant treatment of breast cancer. Approximately 20 percent of breast cancers produce a protein, called HER2, in high amounts, which stimulates the cancer to grow. A targeted drug therapy called trastuzumab (Herceptin®), which attaches to HER2 and blocks it from working has been used since 1998 to treat stage IV (metastatic) breast cancer. In this setting and especially when combined with chemotherapy, Herceptin prolongs life and often reduces the amount of cancer but cannot eradicate it.
Yet when Herceptin and chemotherapy were given as adjuvant therapy for earlier stages of breast cancer, something remarkable occurred. Several large clinical trials demonstrated that women with HER2-positive breast cancer who received Herceptin either with or following chemotherapy had a dramatically reduced risk of cancer relapse than those who received chemotherapy alone. It appears that the Herceptin and chemotherapy combination provides a crucial one-two knockout blow to HER2 breast cancer that neither can provide alone. In short, many individuals in whom breast cancer was destined to return had their destinies powerfully and positively altered: micrometastases were killed so that cancer relapses were averted.
These recent results highlight the fact that cancer therapies are continually improving; recommendations for the adjuvant treatment of cancer change every few years depending on the results of the latest clinical trials. They also demonstrate the vital importance of good clinical trials and the enthusiastic participation of both patients and physicians in this process.
♦ ♦ ♦ ♦ ♦
Dr. Richard Frank is director of cancer research at Whittingham Cancer Center at Norwalk Hospital in Norwalk, CT, and medical director at Mid-Fairfield Hospice in Wilton, CT.
Excerpted with permission from Fighting Cancer with Knowledge & Hope by Richard C. Frank, MD, copyright © 2009 by Richard C. Frank, MD. Published by Yale University Press.
This article was published in Coping® with Cancer magazine, September/October 2009.