Hodgkin’s Lymphoma: An Environmental Scan
Table of Contents
Estimates released in May of 2010 from The Canadian Cancer Society state a total of 930 cases of HL will be diagnosed in Canada this year (Canadian Cancer Society et al. 2010). In 2007, the American Cancer Society referred to HL as an uncommon cancer and reported approximately 8,000 new diagnosed cases (American Cancer Society 2007). However, within all lymphomas; HL is frequently occurring and in the West up to 4 new cases can be expected for every 100,000 (Küppers, Yahalom, and Josting 2006). Epidemiological data consistently demonstrates across all subtypes of HL and in developed countries there is a bimodal or two frequently occurring patterns surrounding the prevalence. One peak in young adults between ages 15 and 34 years and a second peak between ages 55-60 (Adamson and McNally 2005). Specifically, for younger people, it is the most diagnosed cancer in adolescents between 15 and 19 years old (Punnett, Tsang, and Hodgson 2010). This relationship holds across European, Australian, American and Hispanic populations. Concerning individuals of Asian descent, there are fewer cases among younger aged people. Therefore, compared to older adults (over age 40), who have a lower incidence of HL; young people are diagnosed with HL more often (Glaser and Swartz 1990).
More specifically, younger adults tend to develop the HL sub-type, nodular sclerosis more frequently. Furthermore, it has been suggested that the nodular sclerosis sub-type of classical HL is in fact a distinct entity with different epidemiological and other characteristics. This sub-type is more common in females and is less often associated with the Epstein-Barr virus (Mani and Jaffe 2009) whereas among older adults mixed cellularity and lymphocyte depletion sub-types are seen most frequently. In the developing world, there is an absence of the bimodal distribution, there is a peak in boys, lower rates in adults and the most common sub-type is mixed cellularity. Furthermore, in the developing world HL is diagnosed at the advanced stage more often (Aster 2010) (Siddiqui et al. 2006).
Numerous studies conducted globally, for example in India and in North America between 1960 and through the 90’s, demonstrated a consistent consensus that the incidence rate of HL increased among both adolescents and young adults with the preponderance of cases attributed to females with the HL sub-type NS. Conversely, studies in the UK and Europe found decreasing cases of HL in all but males between 15 and 24 and no overall change in incidence rates. A 2006 study in the United States examined Cancer Registry data from 1969 to 1998 and found that there were more new cases of HL even when considering how diagnostic techniques may have resulted in finding more new cases and diagnosing such cases earlier in the disease process over time.