Surgery is almost always part of the treatment plan for early-stage breast cancer. Whether the surgery is mastectomy or lumpectomy depends on a number of factors, including the characteristics of the cancer, a woman’s medical history, and her personal preferences.

Patients have asked me about any links between the type of anesthesia used during breast cancer surgery.

I searched the National Library of Medicine database and could find no high quality evidence suggesting a link between anesthesia and cancer recurrence.

High quality evidence is a large, randomized, prospective trial. This kind of study is considered the gold standard of research. In this case, that kind of trial would likely randomly assign people who’ve been diagnosed with cancer and were going to have surgery to one of several types of anesthesia. Then the people would be followed for many years after surgery, because recurrences can happen, 5, 10, or 20 years after the initial diagnosis. The researchers would collect information on how many of the people in the study had cancer recurrences and then compare that to the type of anesthesia that was used during surgery. That way, they could see if one particular type of anesthesia was linked to a significantly higher number of recurrences that were not just by chance.

But that type of research HAS NOT been done on this topic. There is some weak evidence from studies in mice and test tubes that is suggestive of a link, but this type of evidence doesn’t necessarily translate into a difference for patients. Observational studies in actual patients have had conflicting results.

It’s also very important to know several things:

• These studies were not prospective, they were retrospective. This means that the evidence was already collected for another reason and then the study was designed. The results from retrospective studies are considered weaker than results from prospective studies.
• While we can learn a lot from animal and cell studies, they’re not exactly the same as people. Sometimes what happens in mice doesn’t happen in people.
• According to a review published in 2014, only one very small (129 patients) retrospective study has looked for any links between breast cancer recurrence and type of anesthesia used during surgery. The review calls for randomized clinical trials to be done to help answer the question. I think a better study should be done to provide a conclusive answer to this important question.

These results DO NOT mean that women should avoid breast cancer surgery. They also don’t mean that women have to endure breast surgery while awake. Decisions about surgery depend on many factors. You and your doctor will determine the kind of surgery that’s most appropriate for you based on the stage of the cancer, the “personality” of the cancer, and what is acceptable to you in terms of your long-term peace of mind.

For more information about the types of breast cancer surgery and factors to consider when making your decision, check out the Breastcancer.org Surgery section.