齲齒與頭頸部癌症風險較低有關


  【24drs.com】研究者指出,一口壞牙者可能因禍得福,因為齲齒者的頭頸部鱗狀細胞癌(HNSCC)風險可能較低;一篇案例控制研究中,評估了某綜合癌症中心、牙齒和頜面修復門診的620名成人。
  
  這篇由紐約州立大學Mine Tezal博士等人進行的研究,結果線上登載於9月12日的JAMA Otolaryngology–Head & Neck Surgery期刊。
  
  齲齒最多的33%病患,HNSCC風險是少齲齒或無齲齒者的三分之一(勝算比[OR]0.32);趨勢P值 = .001);此外,齒冠較多的病患,頭頸部癌症風險顯著較低(OR,0.46;趨勢P值= .03)。
  
  齲齒和癌症風險之間的這個負相關,可見於完全禁酒者和從不吸菸的患者,在口腔和口咽癌呈現顯著關係,但是喉部HNSCC則無。
  
  研究者推測,齲齒和HNSCC之間的負相關,可能和蛀牙造成牙菌斑中出現細菌而引起的免疫反應有關。
  
  許多研究顯示,齲齒和相關細菌引起週邊血液單核球的強力Th1免疫反應,促成CD8+ T-細胞反應;而Th2和Th17細胞反應一般和癌症風險增加有關,Th1細胞反應和癌症風險降低有關。
  
  相對的,之前的研究顯示牙周炎(慢性牙齦發炎)和革蘭氏陰性厭氧菌以及牙槽骨喪失之HNSCC風險增加有關;研究者解釋,牙周炎一般會引起Th2和Th17細胞極化免疫反應。
  
  研究世代包括了新診斷有口腔、口咽、喉部鱗狀細胞癌的399名病患(案例組),以及221名沒有癌症或異型增生的新病患(對照組),這些病患都是在相同時期就診於水牛城Roswell Park癌症研究中心的牙科門診。控制診斷時的年紀、性別、婚姻狀態、抽菸、飲酒習慣等多變項模式中,發現齲齒越多則癌症風險越低的關聯。
  
  研究者認為,不需要在良好口腔衛生和頭頸部癌症風險之間做折衝。
  
  Tezalu博士等人寫道,乳酸菌導致脫鈣(齲齒),只發生於牙菌斑中的乳酸菌和牙齒表面接觸時;唾液或粘膜表面上存在這些其他方面有益的細菌,可能可以幫助宿主對抗慢性發炎疾病與HNSCC。我們可以認為,齲齒是某種類型的附帶損害,應發展可降低其風險但可保有乳酸菌之益處的策略。
  
  資料來源:http://www.24drs.com/professional/list/content.asp?x_idno=7010&x_classno=0&x_chkdelpoint=Y
  

Bad Teeth, Good Gums Linked to Lower Head/Neck Cancer Risk

By Neil Osterweil
Medscape Medical News

Bad teeth can be a blessing in disguise for patients, because dental caries (or cavities) can be protective against head and neck squamous cell carcinomas (HNSCC), investigators contend.

In a case–control study, 620 adults at a dental and maxillofacial prosthetics clinic at a comprehensive cancer center were evaluated.

Results of the study, led by Mine Tezal, DDS, PhD, from the State University of New York at Buffalo, were published online September 12 in JAMA Otolaryngology–Head & Neck Surgery.

The 33% of patients with the most caries had one third the risk for HNSCC of patients with few or no cavities (odds ratio [OR] 0.32; P for trend = .001).

In addition, patients with more crowns were at significantly lower risk for head and neck cancers (OR, 0.46; P for trend = .03).

The inverse association between caries and cancer risk was seen in teetotalers and in patients who never smoked, and was significant for oral cavity and oropharyngeal cancers, but not for laryngeal HNSCC.

The investigators speculate that the inverse association between caries and HNSCC might be related to an immune response to the presence of decay-causing bacteria in dental plaque.

"Multiple studies have shown that dental caries and associated bacteria elicit a potent Th1 immune response in peripheral blood mononuclear cells promoting CD8+ T-cell responses. Whereas Th2 and Th17 cell responses have been generally associated with increased risk of cancer, Th1 cell response has been consistently associated with decreased risk of cancer," they write.

In contrast, previous studies have demonstrated a link between periodontitis — chronic inflammation of the gums — and an increased risk for HNSCC associated with the presence of Gram-negative anaerobic bacteria and alveolar bone loss. Periodontitis typically provokes Th2 and Th17 polarized immune responses, the investigators explain.

The study cohort consisted of 399 patients with newly diagnosed squamous cell cancers of the oral cavity, oropharynx, and larynx (case group), and 221 new patients who did not have a diagnosis of either cancer or dysplasia (control group) but were seen during the same time period at the dental clinical at the Roswell Park Cancer Institute in Buffalo.

The link between more cavities and lower cancer risk was detected in multivariate models that controlled for age at diagnosis, sex, marital status, smoking, and alcohol use.

The investigators suggest that there does not need to be a tradeoff between good dental hygiene and risk for head and neck cancer.

"Lactic acid bacteria cause demineralization (caries) only when they are in dental plaque in immediate contact with the tooth surface. The presence of these otherwise beneficial bacteria in saliva or on mucosal surfaces may protect the host against chronic inflammatory diseases and HNSCC. We could think of dental caries as a form of collateral damage and develop strategies to reduce its risk while preserving the beneficial effects of the lactic acid bacteria," Dr. Tezal and colleagues write.

The study was supported by grants for the National Cancer Institute and the National Institute of Dental and Craniofacial Research. The authors have disclosed no relevant financial relationships.

JAMA Otolaryngol Head Neck Surg. Published online September 12, 2013.

    
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