Adjuvant Chemotherapy

Adjuvant chemotherapy is administration of medication as the second part of a two-modality treatment regimen,  Initial treatment is surgery or radiation (or both) and then chemotherapy is given.  Usually the chemotherapy will be applied after all of the known and visible cancer has been removed surgically or with radiation. Adjuvant chemotherapy aims to destroy hidden cancer cells that remain but are undetectable.

Adjuvant means additional. Adjuvant chemotherapy is given to patients after primary treatment, when the doctor thinks there is a high risk the cancer will return. After a primary treatment of surgery or radiation, adjuvant chemotherapy reduces the risk of recurrence. The elimination of undetectable microscopic cancer cells that may have traveled to other parts of the body is the goal of adjuvant chemotherapy.

When adjuvant chemotherapy doesn’t result in a full cure it does make the intervals between a cancer relapse longer. Adjuvant chemotherapy typically begins within three to five weeks of the surgical removal of the cancer and has different treatment lengths depending on the cancer. For breast cancer, the adjuvant chemotherapy is administered for three to nine months. In the case of colon cancer, treatment rarely last more than six months.

Goldie and Coleman’s somatic mutation theory of why cancers develop resistance to chemotherapy (published in 1984) postulated tumors become more heterogeneous when they become bigger.  They develop different kinds of cells (in proportion to the whole tumor) and some of these cells can resist the chemo agent.  That idea pushed doctors into compressing the timeframe of treatment, and starting adjuvant chemotherapy soon after surgery, to stop the remaining cancer cells from proliferating, and, more importantly, mutating to resistant clones.

Neoadjuvant chemotherapy is the administration of drugs before surgery or radiation therapy. The reduction in size of larger tumors, or to prevent metastatic cancer from spreading, is the goal of neoadjuvant chemotherapy. Breast, head, and neck tumors can be more successfully removed after they were shrunk by neoadjuvant chemotherapy.

Adjuvant chemotherapy is used for:

  • Breast cancer
  • Colon cancer
  • Testicular cancer
  • Ovarian cancer
  • Lymphoma
  • Lung cancer
  • Pancreatic cancer

It is commonly used for breast cancer, especially under the following conditions: when cancer cells have been found in the lymph nodes during breast tumor removal surgery, when there was a large tumor that indicated a high possibility of metastasis, in the presence of an aggressive and high-grade pathology, or if a tumor has negative hormone receptors.  Studies show women under 50 reduced their risk of a recurrence by 35 percent, and women over 50 reduced their risk by 20 percent when adjuvant chemotherapy is given.

It is difficult to measure the success of adjuvant chemotherapy in absolutes because the treatment is administered in the absence of detectable amounts of cancerous cells.

elderly chemotherapy patientPatients who went through surgery or radiotherapy to rid their body of cancer are often confused when they are counseled to go through adjuvant chemotherapy. Instead of attacking cancer that is visible in x-rays, CAT scans, or lab results, the adjuvant chemotherapy is designed as a sort of insurance against the threat of possible cancer cells causing new damage in other areas of the body.

The percentages of patients receiving adjuvant chemotherapy vary with the type of cancer. In deciding if a patient should receive the therapy the possible benefit is weighed against the survival rate without adjuvant chemotherapy. A careful evaluation of every patient’s personal situation in collaboration with the oncologist is needed to figure out the best follow up after cancer.  Here are some questions you may wish to ask your doctor.

Note that lower dose regimens of chemotherapy after a primary chemotherapy treatment effort are not adjuvant chemotherapy.  They are called maintenance chemotherapy.

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Sources:

Everyone’s Guide to Cancer Supportive Care by Ernest H. Rosenbaum, M.D, and Isadora Rosenbaum M.A. 2005, pages 41, 544.

Dr. Susan Love’s Breast Book. Susan M. Love, M.D. 2000, page 381.

http://www.mayoclinic.org/diseases-conditions/cancer/in-depth/adjuvant-therapy/art-20046687

Des Guetz G, Uzzan B, Morere J-F, Perret G, Nicolas P. Duration of adjuvant chemotherapy for patients with non-metastatic colorectal cancer. Cochrane Database of Systematic Reviews 2010, Issue 1. Art. No.: CD007046. DOI: 10.1002/14651858.CD007046.pub2