3 RESULTS
3.1 Smoking status and age between patients with unilateral and
bilateral lesions
The number of cigarettes smoked per day didn’t appear significantly
different between patients with unilateral and bilateral lesions (U =
56.9, p = .109 and though it seemed to be higher in the malignancies
group, that was not statistically significant (U = 56, p = .064). The
years of smoking were found to be similar between patients with
unilateral and bilateral lesions (t = 0556, p = .956) and although
patients who developed malignancies reported having smoked for more
time, there was no significant difference when comparing their years of
smoking with those of the patients with non-malignant lesions (t =
-1.24, p = .227). It was age however that was found to be of true
importance, since in our group malignancies were identified in older
rather than younger subjects (t = -2.23, p = .034), but that was not
observed as regards the bilateral presence of lesions (t = -0.98, p =
.332). Table 2 presents the comparison of smoking status and
age between patients with and without malignancies.
3.2 Smoking habits and age in different types of vascular
classification
Moreover, a Kruskal-Wallis test showed no significant statistical
difference in cigarettes smoked per day between lesions that had
different types of intraepithelial papillary capillary loop
classification, χ2 (5) = 9.93, p = .077 (Figure 1 ). No such
difference was found in years smoking either, as determined by a one-way
ANOVA that was also performed, F (5, 9.95) = 2.52, p = .100. Age however
presented a significant effect regarding the vascular classification, F
(5, 12.9) = 3.71, p = .027. Post-hoc comparisons using the Games-Howell
test showed significant difference particularly between the age of
patients in the group of type I lesions (M = 52.7, SD = 1.15) and the
age in the group of type Vb lesions (MD = 63.7, SD = 8.50). Our results
suggest that malignancies had significantly higher chances of developing
in older individuals, when compared to the mildest type I lesions of
vascular classification.
3.3 Smoking habits and age in different types of morphological
classification
A Kruskal-Wallis test showed no
significant statistical difference in cigarettes smoked per day between
different types of morphological classification, χ2 (5) = 4.84, p =
.089. In the same way a one-way ANOVA did not indicate statistical
difference in the years smoking either F (2, 14) = 2.02, p = .170. Age,
according to a one-way ANOVA, was significantly different among
different types of morphological classification types, F (2, 35) = 7.72,
p = .002. The significant difference in age was detected between the
“flat and smooth” type of lesions (M = 51.4, SD = 6.33),p=.002 and the
“rough” type of lesions (M = 61.5, SD = 6.83), p = .001 as indicated
by post-hoc comparisons using the Tukey correction. The results are
depicted in Table 3 .
3.4 Classification of leukoplakia and smoking habits
As mentioned above we have examined a total of 32 vocal cords with
leukoplakia. By 22 of them a low-grade dysplasia has been found. The
rest of them have been diagnosed with a high-grade dysplasia. A
Kruskal-Wallis test showed no significant statistical difference in
cigarettes smoked per day between different types of morphological
classification, χ2 (5) = 4.64, p = .088. In the same way a one-way ANOVA
did not indicate statistical difference in the years smoking either F
(2, 08) = 2.02, p = .1640. The application of Kendal-tau criterion has
shown the grade of dysplasia is correlated to age. By patients with
low-grade dysplasia (n=18) this was estimated by τ=0.73. By those with
high-grade dysplasia (n=14) the correlation was stronger (τ=0.82).
3.5 Contact Endoscopy in non-smoking and smoking subjects
We also tested if there was statistical significance between the
vascularization type of the vocal cords of the healthy subjects (control
group) and the vascularization type of patients suffering from
leukoplakia and malignancy. Vocal cords with type I or type II
vascularization pattern were more likely to belong to patients who have
non-malignant contralateral vocal cords, whereas healthy cords of type
III or IV were more likely to be associated with contralateral
malignancies, according to a Fisher’s exact test that showed statistical
significance, p = .002. In non-smoking subjects we have found that 18 of
them had a type I vascularization. By the rest a type II vascularization
on both sides has been documented.