Incidence trends of colorectal cancer in urban Shanghai, 1973 - 2005 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the time trends of colorectal cancer incidence rates in urban Shanghai from 1973 to 2005.</p><p><b>METHODS</b>Data on the incidence rates of colorectal cancer were obtained from a population-based cancer registry in Shanghai. A total of 32 962 colon cancer patients and 24 662 rectal cancer patients were registered. Population estimation were based on periodic censuses, with age- and sex-specific annual estimates derived for the remaining years. The rates were adjusted to the world standard population by using the direct method. Annul percent changes (APCs) in rates were estimated by means of a linear regression of the logarithm of the respective rates on calendar, weighted by the number of incidence cases.</p><p><b>RESULTS</b>The incidence rates of colorectal cancer increased steadily during 1973 to 2005, the age-adjusted incidence rates of colon cancer increased from 6.09 and 5.70 to 14.70 and 14.35 per 100 000 in male and female respectively. The APCs were 3.03% (t = 14.77, P < 0.01) and 3.21% (t = 22.15, P < 0.01). The rates of rectal cancer increased from 7.68 and 6.51 to 11.45 and 8.28 per 100 000 in male and female respectively. The APCs were 1.34% (t = 7.28, P < 0.01) and 0.93% (t = 7.34, P < 0.01). The top APCs for colon and rectal cancer in female were 5.86% and 2.79% at age above 85 and in male those were 4.64% and 2.38% at age of 80-. The APCs of colon cancer were greater than those of rectal cancer at the groups above 45 years old. The average ages when diagnosed were delayed from 57 - 60 to 66 - 70 during these 33 years. The average diagnosed ages of colon cancer were later than those of rectal cancer slightly (from 2003 to 2005, the onset age of male colon cancer: 68.61 +/- 12.17, male rectal cancer: 66.81 +/- 12.62, t = 4.90, P < 0.01; female colon cancer: 69.20 +/- 12.13, female rectal cancer: 67.75 +/- 12.54, t = 3.81, P < 0.01).</p><p><b>CONCLUSION</b>The incidence rates of colorectal cancer increased steadily during 1973 to 2005, especially for colon cancer. Further research is needed to identify the causes resulting in these changes.</p>

Methods for time trend analysis of cancer incidence rates / 中华流行病学杂志

<p><b>OBJECTIVE</b>To introduce statistical methods of time trend analysis on cancer rates.</p><p><b>METHODS</b>Cancer incidence data collected by the Shanghai Cancer Registry during 1991 to 1999 was used in the analysis to calculate the crude and age-adjusted rates, percent changes (PCs) and annual percent changes (APCs). APCs were estimated by a linear regression of the logarithm on the incidence rates during the nine years. It also introduced a method for partitioning a linear trend in age-adjusted rates into site-specific contributions to the overall floating trend. 95% confidence intervals for the APCs and contributions were described in the paper.</p><p><b>RESULTS</b>A decreasing rates were observed for cancers of stomach and esophagus among both men and women in urban Shanghai from 1991 to 1999. The increasing rates among men would include cancers of colon, rectum, gall bladder, pancreas, prostate, urinary bladder, kidney and leukemia. The rates of cancers among women increased for colon, rectum, lung, breast, gall bladder, endometrium, ovary, urinary bladder and kidney. The changes of above cancers over time were statistically significant (P < 0.05 or P < 0.01), but rates for other cancer sites changed little. The APCs (weighted method) and contributions for the cancers of stomach, esophagus, colon, rectum and prostate were -2.99% and -65.72%, -2.90% and -17.07%, 12.30% and 21.46%, 2.94% and 18.62%, and 3.11% and 15.09% among men, and -6.05% and -39.55%, -1.08% and -35.19%, 2.81% and 28.64%, and 3.69% and 15.70% for the cancers of stomach, esophagus, breast and colon in women, respectively.</p><p><b>CONCLUSION</b>APC, and related statistics could be used to describe and analyze the time trend of cancer rates rather than PC or/and graphical method alone.</p>