The risk factors in common across all low-grade indolent lymphomas include the following:

• Age – incidence of low-grade lymphomas increases with age
• Obesity – high BMI in adulthood and early adulthood may increase the risk of low-grade lymphomas (Abar et al. 2019)
• Family history – individuals with a first-degree relative (parent, child, sibling) with a low-grade lymphoma have a small increased risk of developing NHL
• Race/ethnicity – there is a higher incidence of indolent NHL in white Caucasian populations compared with non-Caucasian ethnicities
• Radiation exposure – patients treated with radiation for other cancers have slightly increased risk of developing a low-grade This risk is greater for patients treated with both radiation therapy and chemotherapy
• Weakened immune system – people with weakened immune systems as a result of immunosuppressive drugs, chronic infection or some genetically inherited syndromes are at a higher risk of developing a low-grade lymphoma
• Autoimmune diseases – people with autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, Sjogren’s disease and coeliac disease may have an increased risk of developing a low-grade lymphoma
• There is a possible association between exposure to glyphosate-based agricultural pesticides and risk of developing a low-grade lymphoma, but a lack of prospective studies limits definitive

Follicular lymphoma

• Gender – women have a slightly higher risk of developing FL than men
• Race/ethnicity – FL occurs more commonly in Caucasian populations
• Viral infections – viruses that have been implicated in developing FL include Epstein-Barr virus, human T-cell lymphotropic virus type I and Kaposi sarcoma-associated herpesvirus

MALT lymphomas

MALT lymphomas, in particular, are associated with a variety of infectious/autoimmune disorders:

• 90 per cent of gastric MALT lymphoma are associated with Helicobacter pylori gastritis
• Ocular adnexal MALT lymphoma may be associated with Chlamydia psittaci
• Cutaneous MALT lymphoma may be associated with Borrelia burgdorferi
• MALT lymphoma of the small intestine and immunoproliferative small intestine disease may be associated with Campylobacter jejuni
• Thyroid MALT may be associated with Hashimoto’s thyroiditis
• Salivary gland MALT may be associated with Sjogren’s syndrome
• SMZL may be more common in those with chronic hepatitis C infection and associated with autoimmune conditions such as haemolytic anaemia and immune

Mantle cell lymphoma

• Gender – men have a greater risk of developing MCL than