乳がんのサルコペニアの有病割合と予後予測

乳がん患者におけるサルコペニアと有病割合と予後予測に関する論文を紹介します。

Adriana Villaseñor, et al: Prevalence and prognostic effect of sarcopenia in breast cancer survivors: the HEAL Study. Journal of Cancer Survivorship Research and Practice, doi: 10.1007/s11764-012-0234-x

対象は乳がんの女性患者471人（ステージI–IIIA）です。サルコペニアはDEXAで四肢筋肉量で評価しています。平均9.2年間のフォローしています。75名がサルコペニアと分類され、フォロー中に92人が死亡しています。うち46人が乳がんによる死亡と判断されました。

多変量解析でサルコペニアは全死亡の独立した予測因子でした（ハザード比2.86、95%信頼区間1.67–4.89）。一方、乳がんによる死亡に関しては統計学的には有意ではありませんでした（ハザード比1.95、95％信頼区間0.87–4.35）。

以上より、サルコペニアに介入して筋肉量を維持・改善することで生命予後が改善するかどうかの研究が望まれるという結論です。

この論文ではサルコペニアとしていますが、その原因は加齢だけでなく悪液質が背景にあることが推測されます。今回の研究では悪液質の診断や多変量解析での調整がありませんので、何ともいえませんが、悪液質の評価と介入のほうがより重要な可能性があります。

Abstract

Purpose

This study aimed to determine the prevalence of sarcopenia and examine whether sarcopenia was associated with overall and breast-cancer-specific mortality in a cohort of women diagnosed with breast cancer (stages I–IIIA).

Methods

A total of 471 breast cancer patients from western Washington State and New Mexico who participated in the prospective Health, Eating, Activity, and Lifestyle Study were included in this study. Appendicular lean mass was measured using dual X-ray absorptiometry scans at study inception, on average, 12 months after diagnosis. Sarcopenia was defined as two standard deviations below the young healthy adult female mean of appendicular lean mass divided by height squared (<5 .45=".45" kg="kg" m="m" sup="sup">2

). Total and breast-cancer-specific mortality data were obtained from Surveillance Epidemiology and End Results registries. Multivariable Cox proportional hazard models assessed the associations between sarcopenia and mortality.

Results

Median follow-up was 9.2 years; 75 women were classified as sarcopenic, and among 92 deaths, 46 were attributed to breast cancer. In multivariable models that included age, race-ethnicity/study site, treatment type, comorbidities, waist circumference, and total body fat percentage, sarcopenia was independently associated with overall mortality (hazard ratio (HR) = 2.86; 95 % CI, 1.67–4.89). Sarcopenic women had increased risk of breast-cancer-specific mortality, although the association was not statistically significant (HR = 1.95, 95 % CI, 0.87–4.35).

Conclusion

Sarcopenia is associated with an increased risk of overall mortality in breast cancer survivors and may be associated with breast-cancer-specific mortality. The development of effective interventions to maintain and/or increase skeletal muscle mass to improve prognosis in breast cancer survivors warrants further study.

Implications for Cancer Survivors

Such interventions may help breast cancer patients live longer.