If you have been diagnosed with cancer and just had a surgeon cut it out, you may wonder why you are being told you may need other treatments like chemotherapy and/or radiation.
Well, over the past several centuries, surgeons have perfected the art of cutting out cancers. Consider breast cancer for example. It was initially believed that cutting out the cancer and immediately surrounding tissues would increase cure rates. Alas, this did not happen. There continued to be a fraction of individuals that had cancer grow back or relapse. Instead, we have realized that surgery does not necessarily have to be so radical. We have learned to minimize surgery and improved on treatments given after surgery to increase cure rates.
We now understand better that in almost all cases of cancer, there is “a large piece” and the “microscopic piece”. I use the term “large piece” to refer to the tumor we can see or feel, that a surgeon can cut out. The “microscopic piece” refers to single cells that float away, and can scatter throughout the body. When we kill these microscopic cells, we reduce the chance of a relapse and increase chances of a cure.
Other treatments given after surgery are called “adjuvant therapies”. The term “adjuvant” is derived from the Latin verb “adjuvare”, which means, “to help”. Adjuvant therapies serve to eradicate microscopic disease.
Here are some examples:
Chemotherapy. This is most widely used, in the vast majority of stage II to III cancers, and occasionally in stage I cancers, depending on the situation. When given for adjuvant therapy, a specified number of cycles is most commonly given, rather than indefinitely. See my prior article about chemotherapy.
Hormone-blocking therapy. Pills like tamoxifen or aromatase inhibitors that block estrogen may be given in the setting of breast cancer. Testosterone blocking treatments may be used in prostate cancer.
Targeted therapy. There are some medications that work by targeting a specific component on a cancer cell, thereby minimizing risk of some rather generalized side effects that may be seen with conventional chemotherapy. Nonetheless, they too, can cause side effects. These drugs fall in the rapidly growing category of targeted therapy. An important example is Herceptin, given in the setting of HER2 positive breast cancer (pertuzumab also falls in this category). Although herceptin does not commonly cause nausea and vomiting, it can affect heart function (because the HER2 mechanism is involved in the heart). See my prior article about breast cancer.
Immunotherapy. These medications target the immune system and may be used as adjuvant therapy for some cancers. An example is ipilimumab that can be used after stage III melanoma has been cut out.
Radiation. Unlike all the above treatments, radiation is directed to a particular area of the body, and so does not address microscopic disease that may have spread far away from the cancer site. Still, there are some situations where radiation therapy does add further to the above, to reinforce “local control.” For example, radiation may be used if the tumor cut out is particularly large or if neighboring lymph nodes are involved by cancer.