Colorectal Ca in Asians With Diabetes
Chinese Singaporeans with diabetes have a 50% greater risk of developing colorectal cancer than nondiabetic, matched controls, Dr. Adeline Seow and her colleagues have reported.
Because the mean body mass index among Asians is 3 kg/m
The researchers examined the incidence of colorectal cancer from 1993 to 1998 in more than 63,000 ethnic Chinese persons in Singapore. All the subjects were cancer-free at baseline, and 9% had diabetes.
After an average follow-up period of 7 years, 636 subjects had developed colorectal cancer. After adjusting for age and gender, the incidence rates were 209/100,000 person-years among diabetics and 140/100,000 person-years among nondiabetics. Compared with nondiabetics, men with diabetes had a 50% higher risk of the cancers, and women with diabetes had a 40% increased risk.
When all subjects were stratified by BMI, diabetics with a BMI of 20–24 had a 70% higher risk of developing the cancer, but there was no trend suggesting an increasing risk with higher BMIs. There was also a significantly increased risk of cancer among diabetics with higher calorie intake (relative risk 1.8) and lower activity levels (RR 1.5), compared with nondiabetics.
T Cells vs. Metastasis in Colorectal Ca
High levels of T cells within tumors correlate with the absence of early metastasis and with prolonged survival of patients with colorectal cancer, a prospective analysis of resected tumors from 959 surgical patients indicates.
The presence of pathologic signs of early metastatic invasion—vascular emboli, lymphatic invasion, and perineural invasion (VELIPI)—was associated with adverse outcomes during a mean follow-up period of 44.5 months, reported Dr. Franck Pagès of the Cordeliers Biomedical Research Center, Paris, and associates (N. Engl. J. Med. 2005;353:2654–66).
The disease-free survival rate at 5 years was 32.4% in the 702 patients with VELIPI-negative tumors and 12.1% in the 257 patients with VELIPI-positive tumors. The median duration of disease-free survival was 26.9 months for patients with VELIPI-negative tumors and 3.3 months for patients with VELIPI-positive tumors.
VELIPI-positive tumors showed evidence of an impaired immune response as assessed by flow cytometry (39 tumors), low-density-array real-time polymerase-chain-reaction assay (75 tumors), and tissue microarrays (415 tumors). For the flow-cytometric analyses, the researchers extracted cells by mechanical dispersion from 39 randomly selected samples. For the PCR assays, the 75 samples analyzed were those of sufficient quality and quantity among 100 randomly selected frozen tumor specimens from the 959-patient cohort. For the tissue microarray analyses, the 415 randomly selected samples were deemed representative of the entire cohort.
Pancreatitis or Pancreatic Ca?
A serum assay that quantifies the MUC1 mucin-type glycoprotein is useful in differentiating between pancreatitis and pancreatic cancer, a study has shown.
The new assay is more sensitive and specific than the standard CA19–9 immunoassay, researchers at the Garden State Cancer Center in Belleville, N.J., reported. The CA19–9 antigen is an oligosaccharide present within the MUC1 mucin-type glycoprotein David V. Gold, Ph.D., and his colleagues used an in vitro enzyme immunoassay with monoclonal PAM4 as the capture reagent and a polyclonal MUC1 antibody as the probe to evaluate sera from 43 healthy subjects, 53 pancreatic cancer patients, and 87 patients with pancreatitis (J. Clin. Oncol. 2006;24:1–7).
Using a cutoff of 10.2 units/mL, 77% of cancer patients, 5% of patients with pancreatitis, and none of the healthy subjects tested positive with the PAM4-based assay.
The study also included 81 patients with malignancies other than pancreatic cancer that express the MUC1 antigen. Colorectal cancer most often tested positive with the PAM4-based assay; 5 of 36 patients with colorectal cancer tested positive.
The sensitivity and specificity of the assay for pancreatic cancer were 77% and 95%, respectively. A direct comparison of the ability of the PAM4 and CA19-9 immunoassays to discriminate between cancer and pancreatitis resulted in a significant difference, “with the PAM4 immunoassay demonstrating superior sensitivity and specificity.” This is because PAM4 “demonstrates a more restrictive reactivity for pancreatic cancer,” Dr. Gold and his associates wrote.
The potential role of the PAM4-based immunoassay in detection of early pancreatic tumors remains to be determined.