This project is winding down. Most of the analyses were performed in past years and our research time this year was spent primarily on writing and editing papers in three areas: (1) analyses of long-term linear trends in cancer incidence and mortality, (2) analyses of cancer incidence and mortality trends that allow for curvature, and (3) analyses of incidence trends for non-Hodgkin's lymphoma in Pennsylvania. Our research in these areas mainly involved age-period-cohort and joinpoint analyses. This research was performed in collaboration with several researchers at the University of Pittsburgh. The three areas of research are described in more detail below. Area 1: We examined cancer incidence and mortality trends in the United States using population-based data from the SEER program. The incidence data were from 1975-2004 and the mortality data were from 1970-2004. We used APC models to investigate the effects of age group, time period, and birth cohort on the rates of cancer in three categories: cancers related to tobacco use, cancers detectable by screening, and all other cancers. By design, time trends observed in the residual category cannot reasonably be attributed to temporal changes in cigarette smoking or screening practices. Incidence and mortality rates were analyzed with respect to long-term trends, which can reflect changes in cancer risk factors. Studying trends in light of known risk factors may indicate unexplained cancer patterns. Specifically, we focused on linear trends in the log-transformed rates, summarized by average annual percentage changes and generational risks. The latter concept assesses relative cancer rates between one point in time and another 25 years (i.e., one """"""""generation"""""""") earlier. Among whites over a 25-year span, cancer incidence in the residual category increased 34% in men and 23% in women, while mortality decreased 14% in men and 18% in women. Similar results were obtained for blacks. Changes in tobacco use and screening practices do not completely explain observed changes in cancer trends over the last three decades. We expect that focusing on the cancers in the residual category will provide clues about the causes of these unexplained increases in cancer incidence. A manuscript reporting this research has been accepted for publication and is currently in press at Cancer. Area 2: We extended our APC analysis to account for non-linear trends. Specifically, we assumed a constant curvature model for the log-transformed incidence and mortality rates, of which linearity is a special case. Again we focused on a residual cancer category, but in addition to tobacco-related and screen-detectable cancers, we also excluded cancers associated with HIV infection. Incidence rates increased in every race-sex group, and factors related to both time period and birth cohort membership appeared to accelerate these increases in women. Mortality rates decreased in black and white men and women, with the declines decelerating in white women but accelerating in the other race-sex groups. Increasing incidence of cancers not related to tobacco, screening, or HIV may signify increasing cancer risks, changing diagnostic practices, or better case ascertainment. Declining mortality may signify improvements in cancer care. We submitted a manuscript describing this research to Cancer Causes and Control. Our paper was reviewed and we were invited to resubmit after making a few changes;we are in the process of making these changes and we plan to resubmit the paper soon. Area 3: We investigated the incidence of non-Hodgkin's lymphoma (NHL) in greater detail, studying the effects of both temporal and demographic factors. We focused on data from the Pennsylvania Cancer Registry (PCR), which is not part of the SEER program, but we also used data from the SEER program for comparison purposes. Data from the PCR were available from 1985 to 2004, so we restricted our attention to the same 20 years for the SEER data. We were primarily interested in analyzing the PCR data, but we also compared and contrasted the Pennsylvania results with the national (SEER) results. Over the 20-year period from 1985 to 2004, the incidence of NHL in Pennsylvania increased annually 1.6% and 2.5% in white and black men and 1.6% and 3.2% in white and black women. National trends were similar, except for smaller increases in white men. Diffuse lymphoma appeared to be the most important component of this increase. The incidence of NHL was higher in Pennsylvania counties with greater percentages of urban residents. We submitted a manuscript to the International Journal of Occupational and Environmental Health. This paper was reviewed and we were invited to resubmit after making some modifications;we revised and resubmitted the paper and we are now awaiting the final decision.
| Han, Yueh-Ying; Dinse, Gregg E; Davis, Devra L (2010) Temporal and demographic patterns of non-Hodgkin's lymphoma incidence in Pennsylvania. Int J Occup Environ Health 16:75-84 |
| Han, Yueh-Ying; Dinse, Gregg E; Umbach, David M et al. (2010) Age-period-cohort analysis of cancers not related to tobacco, screening, or HIV: sex and race differences. Cancer Causes Control 21:1227-36 |
| Han, Yueh-Ying; Davis, Devra L; Weissfeld, Joel L et al. (2010) Generational risks for cancers not related to tobacco, screening, or treatment in the United States. Cancer 116:940-8 |
