Medical Specialty >> Oncology

Doctors Lounge - Oncology Answers

Back to Oncology Answers List

If you think you may have a medical emergency, call your doctor or 911 immediately. Doctors Lounge ( does not recommend or endorse any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned on the Site.

DISCLAIMER: The information provided on is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her physician. Please read our 'Terms and Conditions of Use' carefully before using this site.

Date of last update: 10/21/2017.

Forum Name: Breast Cancer

Question: Precautionary chemo?

 idee - Tue Jun 23, 2009 11:19 pm

Can you tell me what studies say about breast cancer survival statistics concerning mastectomies that were successful in removing all of the cancer and have not metastasized to any other areas......whether following the surgery with chemo as a precautionary measure proves to be of benefit over no chemo.

I don't understand why if the cancer hasn't spread and they removed all of the breast cancer by surgery.....what is it they are trying acomplish with chemo?
 Dr. Tamer Fouad - Sun Sep 06, 2009 9:25 am

User avatar Hello,

To answer your question, the idea behind adjuvant chemotherapy is to kill any remaining microscopic malignant cells that are not removed by surgery. Another important thing to remember, is that breast cancer is considered a systemic disease due to its propensity to metastasize.

When taking an overall look at population statistics, there's been a decrease in the cause-specific mortality from breast cancer in every Western nation over the past decade, and this has been mainly attributed to the use of adjuvant chemotherapy.

As for trials, it has been proven beyond doubt that adjuvant chemotherapy improves cure rates after mastectomy, decreases recurrences and improves survival.[1]

Clinical trials are like controlled experiments so you would want to have two groups of patients: one group receiving chemotherapy after surgery and another group without chemotherapy and follow these patients up to see which group has a better outcome.

Trials like these were conducted in the 70s when it wasn't yet known whether adjuvant chemotherapy was better than mastectomy alone. I am adding a reference to the 20 year follow up of the trial by Bonadonna et al.[2]

Trials such as these would never be allowed nowadays, since it would be unethical to prevent patients from the benefit of chemotherapy for the sake of an experiment. However, in the 70's, when it still wasn't known, many other trials were conducted. A group of statisticians meets every 5 years in Oxford University to report on the follow up results of 60 trials involving some 28,764 women that were conducted in the 1990's.[3] The last report was published in 2005 on the 15 year survival and recurrence rates for these patients.[3]

Adjuvant chemotherapy is not for everyone with breast cancer however, and recently genetic analysis of the tumor sample has allowed a better prediction of who can be safely be excluded from adjuvant chemotherapy.

1. Cancer survivors: living longer, and now, better. Lancet. Dec 18-31 2004;364(9452):2153-2154.
2. Bonadonna, G, Valagussa, P, Moliterni, A, et al. Adjuvant cyclophosphamide, methotrexate, and fluorouracil in node-positive breast cancer: the results of 20 years of follow-up. N Engl J Med 1995; 332:901.
3. Early Breast Cancer Trialists' Collaborative Group (EBCTCG). Effects of chemotherapy and hormonal therapy for early breast cancer on recurrence and 15-year survival: an overview of the randomised trials. Lancet 2005 May;365(9472):1687-717.

| Check a doctor's response to similar questions

Are you a Doctor, Pharmacist, PA or a Nurse?

Join the Doctors Lounge online medical community

  • Editorial activities: Publish, peer review, edit online articles.

  • Ask a Doctor Teams: Respond to patient questions and discuss challenging presentations with other members.

Doctors Lounge Membership Application

Tools & Services: Follow DoctorsLounge on Twitter Follow us on Twitter | RSS News | Newsletter | Contact us