Stimulated by Lee et al 2024.[1]
BCRL – breast cancer-related lymphoedema
key to acronyms
BMI – body mass index
NHIS – national health insurance service
PSM – propensity score matching
IRR – incident rate ratio
CI – confidence interval
HR – hazard ratio
This is another large retrospective cohort study from Korea. The difference from previous papers like this is that the lead author (Ye-Seul Jennifer Lee) has already presented the project to us (BMAS members) last year on the BMAS Scientific Meetings Series 2023.
Jennifer presented preliminary data at the ICMART meeting in Bologna in 2022, and for me it was the first time I had seen such data presented live. I got an impression of how complex the process of data analysis can be in these large retrospective studies.
Breast cancer is the most prevalent cancer in Korean women, but the 5-year survival is over 93% for this group, which compares favourably with the average 5-year survival from cancer in Korea at just under 71%. This means that there is an increasing group of patients who are suffering the side effects of breast cancer surgery as well as other cancer treatments include chemo-, radio-, and immunotherapy.
I was surprised to learn that BCRL is the most common side effect of breast cancer surgery. It can affect between 20% and 50% of women depending on a variety of other risk factors, such as age, BMI, and comorbidities.
This study focussed on a 3-year window (2011 to 2013) to find new diagnoses of breast cancer where there was a record of surgery in the claims database of the NHIS. The team found 39 971 cases, of which 35 153 had received breast surgery and axillary dissection within one year of diagnosis. 2055 of this cohort had received at least 3 sessions of acupuncture between 3- and 6-months post-surgery.
Propensity score matching (PSM) in a 2:1 ratio brought the no acupuncture cohort down from 28 976 to 4102, and the acupuncture cohort to 2052.
There were no statistically significant differences in the incidence of BCRL or mortality between the cohorts (BCRL acupuncture vs no acupuncture IRR: 1.017; 95% CI: 0.868-1.193). It worried me slightly that the mean IRRs for the acupuncture cohort were all marginally higher than 1. But before PSM, BCRL incidence was significantly lower in the acupuncture cohort. Hazard ratios (HRs) in the multivariable analysis were also less than 1 in the acupuncture cohort (in all the models – unadjusted and adjusted), suggesting a lower rate of BCRL.
A major limitation of the Korean NHIS database, from the perspective of acupuncture safety, is that it does not include information concerning the anatomical region of needling. This is clearly relevant to some adverse events, such as pneumothorax (see Post-acupuncture pneumothorax incidence). We have assumed that it is relevant to BCRL, but recent papers have questioned the risks associated with needling the ipsilateral arm.[2,3]
I guess that a large proportion of patients receiving acupuncture following breast cancer in Korea have needles placed bilaterally in the upper and lower limbs and may even have more placed on the surgical side, since myofascial pain following breast surgery is common.[4] That assertion is clearly not good enough to properly exclude the hypothesis that acupuncture needling of the ipsilateral limb could increase the risk of BCRL. So, there is still some milage in being cautious and in further prospective safety research.
References
1 Lee Y-S, Lim Y, Yeo J. Acupuncture Needles and the Risk of Lymphedema After Breast Cancer Surgery: A Retrospective National Cohort Study. Perspect Integr Med. 2024;3:29–36.
2 Ferguson CM, Swaroop MN, Horick N, et al. Impact of Ipsilateral Blood Draws, Injections, Blood Pressure Measurements, and Air Travel on the Risk of Lymphedema for Patients Treated for Breast Cancer. J Clin Oncol. 2016;34:691–8.
3 McDiarmid S, Larocque G. Time to rethink vascular access in patients with breast cancer. Br J Nurs. 2020;29:S32–8.
4 Torres Lacomba M, Mayoral del Moral O, Coperias Zazo JL, et al. Incidence of myofascial pain syndrome in breast cancer surgery: a prospective study. Clin J Pain. 2010;26:320–5.
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