**3.3 Hodgkin's lymphoma**

Hodgkin's lymphoma represents 15% of all lymphomas and accounts for only 0.6% of all cancers diagnosed in the United Kingdom (Cancer-Research-UK, 2011). The age standardised incidence in 2007 was 2.6 per 100,000 population in the UK and 2.8 per 100,000 in the USA (Altekruse et al., 2010) (see Figure 2B). In the UK, age-specific peaks in incidence occur in early adult life (for men at 30 to 34 years and women at 20 to 24 years old) and in later life (over 70 years). Unlike NHL, the incidence of Hodgkin's lymphoma seems to have fallen in the 1970s and has plateaued since the 1980s (see Figure 2D). This may be explained by changes in classification of different types of lymphoma. With treatment, prognosis for Hodgkin's lymphoma is good with around 78% of patients with HL diagnosed in 2007 in the UK predicted to survive for at least 10 years according to calculations by Cancer Research UK. The overall age-standardised survival rate for patients diagnosed with HL in England between 1996 and 1999 was 80% (Coleman, 1999). The Nodular Sclerosis subtype of classical HL is the commonest occurring in 60% of cases and is associated with younger age and more affluent populations.

Many of the risk factors for Hodgkin's lymphoma are similar to those of NHL but certain factors may be more important in the development of HL:

 **Genetic susceptibility** – a family history of Hodgkin's lymphoma appears to have a much more dramatic effect on risk when compared to NHL. Monozygotic twin studies suggest a 99-fold increased risk (Mack et al., 1995) and a first degree relative diagnosed with any haematological malignancy confers a two to three-fold increased risk (Chang

 **Genetic susceptibility** – The sibling or progeny of an affected individual has an approximate two-fold increased risk of developing NHL and there appears to be

 **Exposure to chemical carcinogens** – A number of studies and meta-analyses suggest an increased risk of NHL in individuals with occupational exposure to agricultural pesticides (Merhi et al., 2007), benzene (Steinmaus et al., 2008) and aromatic

 **Diet and obesity** – Dietary factors and the risk of lymphoma are controversial. A recent study from Iowa found a 31% risk reduction for women with a higher intake of fruit and vegetables (Thompson et al., 2010). However, an earlier cohort study did not corroborate this finding (Zhang et al., 2000). NHL appears to be associated with obesity with one meta-analysis showing a relative risk of 1.4 for diffuse large B-cell NHL

Hodgkin's lymphoma represents 15% of all lymphomas and accounts for only 0.6% of all cancers diagnosed in the United Kingdom (Cancer-Research-UK, 2011). The age standardised incidence in 2007 was 2.6 per 100,000 population in the UK and 2.8 per 100,000 in the USA (Altekruse et al., 2010) (see Figure 2B). In the UK, age-specific peaks in incidence occur in early adult life (for men at 30 to 34 years and women at 20 to 24 years old) and in later life (over 70 years). Unlike NHL, the incidence of Hodgkin's lymphoma seems to have fallen in the 1970s and has plateaued since the 1980s (see Figure 2D). This may be explained by changes in classification of different types of lymphoma. With treatment, prognosis for Hodgkin's lymphoma is good with around 78% of patients with HL diagnosed in 2007 in the UK predicted to survive for at least 10 years according to calculations by Cancer Research UK. The overall age-standardised survival rate for patients diagnosed with HL in England between 1996 and 1999 was 80% (Coleman, 1999). The Nodular Sclerosis subtype of classical HL is the commonest occurring in 60% of cases and is associated with younger age

Many of the risk factors for Hodgkin's lymphoma are similar to those of NHL but certain

 **Genetic susceptibility** – a family history of Hodgkin's lymphoma appears to have a much more dramatic effect on risk when compared to NHL. Monozygotic twin studies suggest a 99-fold increased risk (Mack et al., 1995) and a first degree relative diagnosed with any haematological malignancy confers a two to three-fold increased risk (Chang

amongst individuals with a BMI ≥ 30 kg/m2 (Larsson and Wolk, 2007).

treatment with a gluten-free diet (Silano et al., 2008).

concordance in NHL subtype (Altieri et al., 2005).

hydrocarbons (Miligi et al., 2006).

**3.3 Hodgkin's lymphoma** 

and more affluent populations.

factors may be more important in the development of HL:

infection has been implicated (Kawashima et al., 1994). A recent meta-analysis suggests an 8-fold increased risk of NHL in post-transplant patients (Grulich et al., 2007b). **Autoimmune conditions** – Conditions such as autoimmune haemolytic anaemia, systemic lupus erythematosus and Sjögren's syndrome, where there is a longstanding stimulation of the immune system have been shown to carry an increased risk of NHL but the exact mechanisms remain poorly understood (Ekstrom Smedby et al., 2008). Coeliac disease is associated with T-cell lymphoma and less frequently, B-cell lymphoma (Chandesris et al., 2010, Oruc et al., 2010). This risk can be reduced by et al., 2005, Goldin et al., 2004). Studies from the USA suggest racial differences in susceptibility with lower risk in blacks than whites (Glaser, 1991).

