Can nerve blocks improve survival after breast cancer surgery?

Can nerve blocks improve survival after breast cancer surgery?

by ih-nfa admin

Is it possible that the type of anesthesia administered for mastectomy can influence long-term survival? The short answer is probably yes.

A paper from Dublin, Ireland (my home town!) in 2006 studied about 130 patients undergoing mastectomy for breast cancer. They were followed up for 3 years. About half the patients received paravertebral blocks combined with general anesthesia and the other half received general anesthesia and morphine for postoperative pain.

Thoracic paravertebral block with ultrasound
Figure 1: Thoracic paravertebral block with ultrasound

Paravertebral blocks consist of injections made on the side of the spine which numb the nerves of the chest wall for many hours. They are performed before surgery under light sedation, sometimes with the help of ultrasound guidance (Figure 1).

In the paravertebral group, 94% of women were free of metastases and had no recurrence. In contrast, 77% in the general anesthesia-morphine group were cancer-free at their 3-year follow-up. Many anesthesiologists, myself included, were confounded! How could anesthesia, given for just a few hours, have such a profound influence on survival so many years later?

Surgery is a stressful time. Not only is there psychosocial stress (which is harmful), but also the immune system takes a beating. Surgery results in metabolic, neuroendocrine, and inflammatory responses, which can be particularly deleterious in a cancer patient. The body’s response to surgical stress increases the likelihood of metastatic spread of cancer. The operation itself also increases the chances of metastases during surgical resection, resulting from cancer cells entering the circulation. Also, poorly controlled pain leads to a deficit in natural killer cells (NK cells), a type of white blood cell that fights cancer.

Cancer spread is associated with decreased T lymphocyte function and decreased NK cell activity, both of which can result from the “stress” of surgery. A significant fall in core temperature (hypothermia) can also stress the immune system, making patients susceptible to wound infections.

The operating room is a hostile environment!

All in all, the time frame during which surgery takes place, known as the peri-operative period, is a vulnerable time, and can have long-standing consequences, if not managed properly.

So...let’s just give lots of morphine to control pain and keep patients nice and warm? Right?

Unfortunately it is not so simple; in fact, it’s rather complicated. Morphine itself can significantly depress the immune system. In animals it is pro-angiogenic (increases blood flow in tumors) and promotes growth of breast cancer. Of course animal studies need to be taken “with a grain of salt.” That being said, there has been a trend to limit the use of strong pain medication during cancer surgery and control pain with other methods.

Enter the role of nerve blocks. Nerve blocks, or regional anesthesia, have a number of advantages, one of them being to preserve immune function during anesthesia. There have been a number of studies showing improved survival following mastectomy when paravertebral blocks are utilized. Patients use less morphine. An additional benefit may include less chronic pain, many months later. Most of these studies are small and retrospective in nature. Larger studies are in progress, but so far, there appears to be a benefit.

PEC 1 block with ultrasound
Figure 2: PEC 1 block with ultrasound image 

Serratus plane block with ultrasound
Figure 3: Serratus plane block with ultrasound image 

A number of other block techniques have recently been developed, including the PEC 1 and serratus plane block, which are pictured above (Figures 2 & 3). These provide effective pain relief and have expanded our armamentarium in controlling pain for major breast surgery.

If you are scheduled for major breast surgery or reconstruction, we may employ these cutting-edge techniques to minimize surgical stress and decrease opioid consumption. We also utilize a number of non-narcotic medications to help control your pain.

Did I mention that we perform these blocks in a quiet zone in the hospital, and we employ music and aromatherapy to decrease overall stress?

Seriously, yes we do!

Edward M. Lee, MD, is an anesthesiologist with NFAC. He has an interest in regional anesthesia and has developed many pain management protocols. He has published a number of articles in this field and is spearheading pain control pathways for breast cancer surgery at St. Vincent’s Medical Center, Riverside. He is an avid landscape photographer in his spare time.

Edward Lee, MD