By Carol L. Kornmehl, M.D., FACRO
Why do people with breast cancer need chemotherapy? The reason is that despite the best efforts of the healthcare team to remove all traces of the tumor, breast cancer can still recur. Even early stage breast cancer can return months to years after the original diagnosis and treatment.
It can come back as a local recurrence (in the treated breast) or as a distant recurrence, also known as metastatic disease, elsewhere in the body, such as the bones, lungs, liver, or other organs. Due to this concern, many oncologists prefer to err on the side of over treating their patients with chemotherapy, lest the person be under treated and sustain a recurrence.
There are certain traditional prognostic factors that influence a doctor’s decision to prescribe chemotherapy. These include the age and general health of the person as well as the size of the breast tumor, the status of the lymph nodes (positive versus negative), and the presence or absence of estrogen receptors on the tumor. Small tumors with positive estrogen receptors and negative lymph nodes tend to be less aggressive.
Examining the statistics, perhaps up to 15 out of 100 (15%) of patients with less aggressive tumors will develop a recurrence. Until recently, to save the lives of those 15 people, medical oncologists needed to treat all 100 patients, as they did not have the tools to identify which of the 100 patients were the 15 who were bound to recur. This meant that 85 out of the 100 people were over treated with chemotherapy.
The question then arises: which of these people can be comfortably spared chemotherapy, as well as its side effects? Also, of those people who undergo a lumpectomy and need breast radiation therapy, who can avoid the delay in radiation therapy imposed by the need to complete chemotherapy first?
To answer this question, a new diagnostic test that measures the likelihood of breast cancer recurrence has been developed. It also assesses the benefit from chemotherapy. The test is called Oncotype DX™ and it is appropriate for breast cancer patients who are:
- Newly diagnosed
- Stage I or II (early stage)
- Lymph node-negative
- Estrogen receptor positive and
Those who will be treated with tamoxifen, an oral medication that interferes with the harmful effect of estrogen on breast cancer cells.
All breast cancer tumors are genetically unique. Many of the genetic differences between individual tumors influence the likelihood that the cancer will recur. These differences are associated in part with the level of expression of a certain group of cancer-related genes. Oncotype DX™ is the first cancer test that uses the unique genetic expression the patient’s tumor to quantify the likelihood that breast cancer will recur.
Oncotype DX™ examines the expression of the aforementioned specific group of genes and uses a mathematical equation to translate it into a Recurrence Score™. The Recurrence Score™ accurately quantifies the likelihood of distant recurrence, and its predictive power exceeds that of the previously described standard prognosticators.
The results are scored in the lowest, intermediate, and highest risk range. Oncotype DX™ results increase confidence that the treatment plan is tailored to the individual patient by helping physicians determine who will benefit the most from chemotherapy.
Clearly, the highest risk people will be advised to accept chemotherapy. The lowest risk group can forego chemotherapy. The greatest controversy lies with the intermediate risk group.
Therefore, a randomized clinical trial is currently examining what is the best approach for the intermediate risk population. The study will accrue nearly 10,000 people and participants will be followed for at least five years.
The good news is that with the advent of this new diagnostic test, people can be selected more carefully for chemotherapy. These people can then have the peace of mind of knowing that they are not leaving any stone unturned and are doing the best they can to minimize the likelihood that their cancer will recur. On the flip side, low risk people can be advised to waive chemotherapy and have a greater comfort level that their disease won’t be likely to recur as a consequence.
Dr. Kornmehl is a board certified radiation oncologist at St. Mary’s Passaic Hospital, Passaic, NJ, and author of the critically acclaimed consumer health book, “The Best News About Radiation Therapy” (M. Evans, 2004). Her Website is www.RTSupportDoc.com .
Copyright 2007 by Carol L. Kornmehl. All rights reserved. No part of this article may be reproduced without express written consent by the author.