SAN FRANCISCO — Women with breast cancer appear to live longer and have less chance of a cancer recurrence if they receive a paravertebral nerve block combined with general anesthesia during their cancer surgery, a study from Denmark has found.
This double-blind study of 77 patients is the first randomized prospective clinical trial to compare the effect paravertebral block plus general anesthesia has on breast cancer recurrence with general anesthesia alone, the researchers say.
They report that women treated with the combined anesthetic technique were approximately 3 times less likely to have had a cancer recurrence and to have died of breast cancer at least 6 years after mastectomy or lumpectomy than women treated with general anesthesia.
"Anesthesiologists should use regional anesthesia as much as possible during cancer surgery, because it seems to improve survival and cancer recurrence and is without the potential side effects of morphine," senior researcher Palle Carlsson, MD, DMSc, associate professor in the Department of Anesthesiology at Aarhus University Hospital in Denmark.
However, breast cancer experts approached by Medscape Medical News said it is too early to incorporate these findings into clinical practice.
The role of regional anesthesia in cancer recurrence remains intriguing but speculative," said Daniel Sessler, MD, anesthesiologist, professor, and chair of the Department of Outcomes Research at The Cleveland Clinic, who is heading an ongoing phase 3 trial addressing this issue.
It is possible that paravertebral block improves outcomes by reducing surgical stress and increasing the number of natural killer cells, which are vital to the immune system and the body's defense against cancer, Dr. Carlsson explained. However, the women with better outcomes also had less postoperative use of opioids, and opioids are known to decrease natural killer cells, he added.
Results Presented at ASA Meeting
Asser Oppfeldt, MD, an anesthesiology resident at Aarhus University Hospital, presented the findings here at American Society of Anesthesiologists 2013 Annual Meeting.
In the study group, approximately two thirds of breast cancer patients underwent mastectomy and one third underwent lumpectomy and sentinel node biopsy.
All patients received 4 to 6 paravertebral injections from level C7 to T5 on the surgical side and standardized anesthesia with propofol and doses of fentanyl or alfentanil as needed.
In addition, 39 patients were randomly assigned to receive nerve block with 0.5% ropivacaine 30 mL, and 38 patients received a placebo of an equivalent volume of isotonic saline.
There were no statistically significant differences between the treatment and placebo groups in mean age (57.6 vs 57.2 years), body mass index (23.8 vs 24.4 kg/m²), or preoperative chemotherapy (5% vs 11%). Cancer characteristics, including tumor size, histological grade, lymph node status, and estrogen-receptor status, were also similar in the 2 groups.
The researchers searched the patients' medical records at least 6 years after the procedure to determine the number of deaths and breast cancer recurrences. One patient in each group died of causes other than breast cancer.
They found significant between-group differences in both recurrence and mortality.
Table. Recurrence and Mortality Outcomes of Patients With Breast Cancer
| Outcome | Ropivacaine, % (n = 39) | Placebo, % (n = 38) | P Value |
| Local or metastatic recurrence | 13.0 | 37.0 | .02 |
| Overall mortality | 10.0 | 32.0 | .03 |
| Breast cancer mortality | 7.7 | 29.0 | .03 |
In addition, there was significantly less postoperative opioid use in patients whose cancer did not recur (45.0 vs 58.8 mg morphine-equivalent; P = .02).
There are no plans for a larger study, Dr. Carlsson said.
Too Small to Change Practice
The study did not have enough patients for the results to alter clinical practice. "It's too small to change our routine," said Kevin Bethke, MD, a breast cancer surgeon at Northwestern University Hospital in Chicago, who was not involved in the study. "But it's a great start."
A strength of the study is that it used only 1 regional anesthetic technique, Dr. Bethke told Medscape Medical News.
However, Dr. Carlsson said anesthesiologists at his hospital now use a different postoperative pain relief system for cancer surgery. The ON-Q PainBuster (I-Flow Corp) system allows them to infuse local anesthetic into the surgical wound through a catheter with a balloon, which is left in place for 1 to 2 days. They switched techniques, he said, because "it is easier and safer than paravertebral block and achieves the same amount of pain relief."
They are not yet investigating this technique for any effect on cancer recurrence, he said.
Dr. Carlsson acknowledged that the adjunctive use of regional anesthesia in cancer surgery might not gain acceptance until researchers find the mechanism of action or until results are obtained from a much larger prospective study.
Such a study is underway. The Regional Anesthesia and Breast Cancer Recurrence trial (NCT00418457), headed by Dr. Sessler, is a phase 3 multicenter trial sponsored by the Outcomes Research Consortium. Patients with stage I, II, or III breast cancer undergoing mastectomy are being randomly assigned to thoracic epidural or paravertebral anesthesia/analgesia, or to sevoflurane anesthesia and morphine analgesia.
Approximately 600 patients have been enrolled so far, Dr. Sessler reported.
That study was designed 7 years ago for 1500 patients with a 10-year follow-up. It will need many more patients than that to be adequately powered, given the decreasing incidence of breast cancer recurrence, Dr. Sessler told Medscape Medical News.
The authors have disclosed no relevant financial relationships.
American Society of Anesthesiologists (ASA) 2013 Annual Meeting: Abstract 4253. Presented October 15, 2013.
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου