Abstract
Background/Aims
Colorectal adenoma and cancer are known to be associated with obesity. Leptin, an adipo-cyte-derived hormone that plays a crucial role in obesity has been suggested as a growth factor in colon cancer. However, the association between adenoma and leptin remains controversial. We evaluated the leptin expression in human colorectal adenoma and its correlation to clinicopathologic factors.
Methods
Leptin expression was assessed by immunohistochemistry in 91 samples of colorectal adenoma larger than 5 mm, which were removed by endoscopic polypectomy. All patients underwent colonoscopy for cancer screening at Seoul Paik Hospital from 2007 to 2008 and we only included the patients less than 50 years of age. Leptin expression and its relationship with clinicopathologic features were analyzed.
Results
Eighty samples were available for the interpretation of leptin expression and showed positive in 42 (52.5%) cases and negative in 38 (47.5%) cases. As body mass index (BMI) increased based on World Health Organization (WHO) classification the positivity of leptin expression also increased (p trend=0.02). In leptin positive group, the correlation of leptin expression with adenoma size and histological showed positive tendency without statistical significance.
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![]() | Fig. 1.Immunohistochemical staining of leptin in colon adenomatous tissue. Leptin immunoreactivity was strongly identified in the cytoplasm of the colonic epithelial cells. (A) Positive leptin expression, (B) negative leptin expression (×200). |
![]() | Fig. 2.Correlation between leptin expression and BMI. As BMI increased, the positivity of leptin expression increased (p trend=0.02). 1, BMI<18.5; 2, 18.5≤ BMI<25; 3, 25≤ BMI<30; 4, BMI≥30. BMI, body mass index; WHO, World Health Organization.∗ BMI category was divided by WHO classification of obesity. † Chi-square test for linear trend. |
Table 1.
Clinicopathologic Variables of 80 Patients with Colorectal Adenoma
Variables | N (%) | |
---|---|---|
Sex | Male | 68 (85.0) |
Female | 12 (15.0) | |
Age (years) | 42.4±5.3∗ | |
BMI (kg/m2) | 24.4±3.2∗ | |
Leptin | Positive | 42 (52.5) |
Negative | 38 (47.5) | |
Polyp size (cm) | 0.9±0.9∗ | |
Polyp number | 1.8±1.1∗ | |
Location | Left colon | 47 (58.7) |
Rectum | 18 (22.5) | |
Sigmoid colon | 21 (26.3) | |
Descending colon | 8 (10.0) | |
Right colon | 33 (41.2) | |
Transverse colon | 3 (3.8) | |
Ascending colon | 24 (30.0) | |
Cecum | 6 (7.5) | |
Pathology | Tubular | 68 (85.0) |
Villotubular | 11 (13.8) | |
Villous | 1 (1.3) | |
Dysplasia | Low | 43 (53.8) |
Low to high | 22 (27.5) | |
High | 15 (18.8) | |
BMI, body mass index. |
Table 2.
Correlation between Leptin Expression and Clinicopathologic Variables
Variables | Leptin expression, n (%) | OR (95% CI) | p-value | ||
---|---|---|---|---|---|
Negative | Positive | ||||
BMI (kg/m2) | <25 (n=42) | 24 (57.1) | 18 (42.9) | 2.29 (0.93-5.61) | 0.07 |
≥25 (n=38) | 14 (36.8) | 24 (63.1) | |||
23.6±3.0∗ | 25.0±3.3∗ | 0.05 | |||
Gender | Male (n=68) | 31 (45.6) | 37 (54.4) | 0.60 (0.17-2.07) | 0.61 |
Female (n=13) | 7 (58.4) | 5 (41.6) | |||
Age | ≤40 (n=26) | 16 (61.6) | 10 (38.4) | 2.33 (0.89-6.07) | 0.08 |
>40 (n=54) | 22 (40.5) | 32 (59.5) | |||
41.7±5.2∗ | 43.1±5.38∗ | 0.24 | |||
Size | <1 cm (n=47) | 24 (51.1) | 23 (48.9) | 1.42 (0.58-3.47) | 0.44 |
≥1 cm (n=33) | 14 (42.4) | 19 (57.6) | |||
0.8±0.3∗ | 1.1±1.2∗ | 0.21 | |||
Number | <3 (n=67) | 30 (44.8) | 37 (55.2) | 0.50 (0.15-1.71) | 0.27 |
≥3 (n=13) | 8 (61.5) | 5 (38.5) | |||
Location | Left (n=47) | 24 (51.1) | 23 (48.9) | 1.42 (0.58-3.47) | 0.44 |
Right (n=33) | 14 (42.4) | 19 (57.6) | |||
Pathology | Tubular (n=68) | 32 (47.1) | 36 (52.9) | 0.53 (0.14-2.03) | 0.35 |
Villotubular (n=11) | 5 (45.5) | 6 (54.5) | |||
Villous (n=1) | 1 (100) | 0 (0) | |||
Dysplasia | Low (n=43) | 22 (51.2) | 21 (48.8) | 1.46 (0.73-2.91) | 0.28 |
Low to high (n=22) | 11 (50) | 11 (50) | |||
High (n=15) | 5 (33.3) | 10 (66.7) |
Table 3.
Multivariate Analysis of Leptin Expression for Clinicopathologic Variables of Patients with Colorectal Adenoma
Variables | Coefficient | OR | 95% CI | p-value |
---|---|---|---|---|
BMI∗ | 0.85 | 2.34 | 0.98 to 5.58 | 0.05 |
Age | 0.73 | 2.08 | 0.78 to 5.57 | 0.15 |
Size† | 0.30 | 1.35 | 0.50 to 3.68 | 0.56 |
Pathology | 0.79 | 0.45 | 0.13 to 1.63 | 0.22 |
Dysplasia grade | 0.42 | 1.52 | 0.77 to 2.98 | 0.23 |
Polyp number | 0.35 | 0.71 | 0.43 to 1.16 | 0.17 |
Location‡ | 0.13 | 1.14 | 0.41 to 3.20 | 0.80 |