Fogorvosi szemle, 2007 (100. évfolyam, 1-6. szám)

2007-10-01 / 5. szám

256

FOGORVOSI SZEMLE ■ 100. évf. 5. sz. 2007.

was characteristic in the control group: 37 of the 52 cases (71.2%) (Table IV). The histological results revealed a more aggressive tumor invasion in the type- 2 diabetes group as compared with the control group; the difference between the two groups was significant

(p<01).

OC has a poor prognosis, with a 5-year survival rate of 50% to 55% [41]. Local recurrence typically occurs relatively early, most often within 1 to 2 years. Because tumor progression is considerably influenced by TNM stage, our cases were homogenized, and only T2-T3 cases were included.

Presumably, the more rapid tumor progression in DM may be caused by different factors [43]. The main promoting factor of tumor spread in DM may be the hyperglycemia, as a result of which the tissue responses may change. It has been confirmed that the oxidation equilibrium is also disturbed in DM2 [3]. In response to the chronic hyperglycemia, increased amounts of AGEs may be formed, which promote the deliberation of further free radicals, induce the production of cytokines and growth factors and damage the structure and function of various extracellular matrix materials [51]. All these processes facilitate tumor invasion. Elevated matrix metalloproteinase level in DM2 plays an important role in both direct and metastatic tumor spread [9], Increased RAGE expression appears to be closely associated with the invasiveness of OC [5].

In DM there is an excessive glucose supply in the serum, an increased Glut-1 expression and glucose transport activity as compared with physiologic glucose concentrations [37], Glut-1 has an important correlation with human malignancies. In OC cases, a significant relationship between disease-related death and Glut-1 expression was observed; a high Glut-1 level predicted shorter survival [27, 42].

Smoking has well-known harmful effects in terms of both OC and DM2 [24, 25]. In the present study, the percentage of smokers was not higher in the DM2 group than in the control group. This suggests that in our gingival cancer cases the diabetic tissue derangement seems to be stronger factor than smoking for the progression of OC.

All these data permit a supposition that DM2 may be considered a prognostic factor in cases of gingival cancer, suggesting an unfavorable course.

Conclusions

The literary data and our results on OC cases support the strong association of DM2 with increased cancer risk at several sites. Moreover, DM2 has a significant impact on the local spread and metastatic progression of cancer. Among OC patients DM2 has a close correlation with a higher rate of overall mortality, local tumor recurrence and metastatic spread.

The associations between insulin resistance and

malignancies reveal new possibilities in the prevention and treatment of cancer. Healthy diet, physical activity and weight loss increase insulin sensitivity, and decrease the risk for both cardiovascular diseases and malignancies. In patients with cancers at several sites (breast, colon, prostate, oral mucosa, etc.) tumor progression may be hampered by maintenance of the euglycemia and a healthy lifestyle.

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