睡眠醫學-睡眠窒息症與腫瘤

雖然現代醫學已經比以前進步了不少，癌症仍然是人類的大患，因此科學家正努力尋找探索各種癌症的成因及治療方案。而睡眠窒息症的兩大特色-間歇缺氧(intermittent hypoxia)及睡眠分裂(sleep fragmentation)正正有致癌性(having carcinogenic properties)和引發更惡腫瘤及治療失效(inducing more aggressive cancer and resistance to the treatment of a preexisting tumor)的效果(1,2)。

第一個首先發現睡眠窒息症與腫瘤有關的研究在2013年發表(3)，這個科研有4910個病人參與，它顯示各類型腫瘤的發病率(incidence)都會隨病人晚間缺氧時間(nighttime with oxygen saturation < 90%)增長而上升。但同期另一較大型(8783個病人)研究並不能複製出同一結論(4)。而稍後一個更大(9629個病人)的研究一樣無法得出睡眠窒息症與腫瘤有關的結論(5)。但兩個臺灣的研究(6,7)分別認為睡眠窒息症與乳癌及原發腦腫瘤有關。一個超巨型(34,848個睡眠窒息症病人)的薈粹分析(8)証實人若患上睡眠窒息症，那他有腫瘤的機會大增(relative risk ,1.53)。另一更超巨型(68,422個腫瘤病人)的嵌套病例對照研究( nested case control study)(9)發現睡眠窒息症病人有較高風險患上乳癌(HR=2.1)、鼻癌(HR=5.96)及前列線癌(HR=3.39)。

在2012年，以Wisconsin population based的研究(10)發覺腫瘤病人的睡眠窒息症越嚴重，他們的預後(prognosis) 越差。綜合其他研究(3,5,7,10,11):少於65歲、男性、無日間嗜睡、非肥胖及沒有接受睡眠窒息症治療的人會有較高的腫瘤發病率和較差的預後。在眾多腫瘤中，自然以患有頭或頸腫瘤的病人有較高機會有睡眠窒息症(12,13)。

大家要留意以上每一個研究都有自身的不足或缺點，所以我們暫不能肯定說睡眠窒息症會引發腫瘤或使之預後變差。我們需要更多科研去解答多個未解的疑團。

參考文獻:

1.  The polymorphic and contradictory aspects of intermittent hypoxia. Am J Physiol Lung Cell Mol Physiol. 2014;307(2):L129-L140.

2.  Fragmented sleep accelerates tumor growth and progression through recruitment of tumor associated macrophages and TLR4 signaling. Cancer Res. 2014;74(5): 1329-1337.

3.  Association between obstructive sleep apnea and cancer incidence in a large multicenter Spanish cohort. Am J Respir Crit Care Med. 2013;187(1):99-105.

4.  Symptoms of sleep-disordered breathing and risk of cancer: a prospective cohort study. Sleep. 2013;10(10):1429-1435.

5.  Obstructive sleep apnea and the prevalence and incidence of cancer. CMAJ. 2014;186(13):985-992.

6.  Sleep apnea and the subsequent risk of breast cancer in women: a nationwide population based cohort study. Sleep. Med. 2014;15(9):1016-1020.

7.  Sleep apnea increased incidence of primary central nervous system cancers: a nationwide cohort study. Sleep Med. 2014;15(7):749-754.

8.   Association between sleep-disordered breathing, obstructive sleep apnea, and cancer incidence: a systematic review and meta-analysis. Sleep Med. 2015;16(10):1289-1294.

9.  Risk of cancer in patients with insomnia, parasomnia, and obstructive sleep apnea: a national nested case-control study. J Cancer. 2015;6(11):1140-1435.

10.  Sleep-disordered breathing and cancer mortality: results from the Wisconsin Sleep Cohort Study. Am J Respir Crit Care Med. 2012;186(2):190-194.

11.  Obstructive sleep apnea is associated with cancer mortality in younger patients. Sleep. Med. 2014;15(7):742-748.

12.The ocurrence of sleep-disordered breathing among patients with head and neck cancer. Laryngoscope. 2011;111(6):1917-1919.

13.  High prevalence of obstructive sleep apnea among patients with head and neck cancer. J Otolaryngol. 2005;34(5):304-311