Changing disease patterns in South Asians in the UK

Abstract

Cancer is perceived to be a low priority public health issue in South Asians. Yet changing lifestyles and environments towards those of the majority population are shifting epidemiological patterns. Similar patterns will occur in other disease areas. Lack of community awareness of these changes will result in increased exposure to risk factors, poor uptake in screening and delayed clinical presentation.

The UK's South Asian population, the largest minority ethnic group at 4% of the total population, ¹ are known to have an elevated risk of coronary artery disease—hence research on ethnic differences in disease has concentrated on this area. ² In contrast, South Asians have a lower incidence of cancer than the general population, with standardised incidence ratios (SIRs) of all malignant neoplasms reported as 68% lower in males and 48% lower in females, ³ whilst standardised mortality ratios for all cancers have been reported between 58 in Indian men at their best to 85 at their worst in Bangladeshi men. ⁴

An epidemiological transition

Economic development has resulted in an increased uptake of sedentary habits, tobacco use and high-fat diets, leading to the concept of the epidemiological transition as originally described by Omran. ⁵ Increasing adoption of the detrimental aspects of the developed world lifestyle is resulting in a shift of epidemiological patterns of cancers in South Asians living in the developed world towards that of the majority population. Rates of cancer in South Asians in England, though lower than rates in the rest of the English population, are higher than rates in the Indian subcontinent. ⁶ The incidence of breast cancer is increasing in South Asians, ⁷ and although lung cancer mortality is lower among most South Asian populations than the general population of England and Wales, it is the most common cancer among South Asian men and its incidence is on the increase. ⁸

Health protection around cancer in South Asians has focused on ethnic-specific issues such as the increased risk of oral cancer from bidi smoking and chewing tobacco, habits which are prevalent in some South Asian communities, ⁹ and liver cancer due to the increased prevalence of hepatitis B in this ethnic group. ⁶ However, the most common cancers in ethnic minorities are now the same as those of the general population—breast cancer is the most common malignancy among female South Asians and lung cancer the most common malignancy among male South Asians in the UK. ¹⁰ All-cancer mortality in South Asian migrants has been found to increase with duration of residence in England and Wales, even after adjusting for socioeconomic position. ¹¹ If lung cancer mortality reflects smoking habits of populations 20—30 years previously, as has been proposed, ³ the likely progression from contemporary behavioural changes to future incidence and mortality data is all too predictable.

Worse access to health care

Though smoking rates in ethnic minorities remain overall relatively lower than in the majority population, it is of great concern that 43% of Bangladeshi men smoke compared to the national average of 27%. ⁸ Yet despite high levels of motivation to quit, Bangladeshis have been found to tend to rely on willpower rather than health service interventions, resulting in poor quit rates, ¹² whilst ethnic minority patients were significantly less likely to receive advice on smoking cessation in one study. ¹³ Much of the UK Bangladeshi community are classified as having low socioeconomic status, high rates of unemployment and low levels of formal female employment, ¹⁴ and with higher smoking rates being found in inner-city ethnic minority communities, ¹⁵ the finding that those in higher social classes have higher quit rates ¹⁶ is a further source of inequity.

Differential uptake rates for screening by ethnic group have also been reported. One pilot study on uptake of colorectal screening for ethnic groups reported significantly lower rates amongst South Asians, ¹⁷ despite increasing developed world influences on dietary patterns. ¹⁸ Different groups are characterized by different dietary patterns, but such patterns are not permanent, being influenced by the background cultural environment. With the introduction of mass screening in the UK for colorectal cancer, uptake in all minority ethnic groups needs to be monitored and reasons for any differential uptake rates observed investigated.

Implications for public health

The tendency to emphasise the importance of cancers such as those of the head and neck among South Asians (because those cancers are relatively more common than in the majority UK population) ignores the wider picture of absolute numbers of cancer cases. ¹⁰ Cancer is used an example here, but there will be other examples of disease areas where, with increased time since migration and increasing life expectancy amongst ethnic minorities, disease patterns will start to resemble that of the majority population. This was highlighted over 10 years ago. ¹⁹ Community awareness of this shift in epidemiology and access to appropriate preventive and curative services for them needs to improve.

As early signs of changing mortality patterns appear amongst ethnic minorities with acculturation, and with behavioural changes (such as smoking uptake) predating mortality changes by 20-30 years, waiting for rigorous mortality data for ethnic minorities may be less important than implementing health protection programmes now to include all ethnic minorities. A piecemeal approach similar to that applied to reducing smoking (spanning nearly half a century from the seminal study by Doll and Hill in 1950 to the first comprehensive preventive strategy, the government white paper ‘Smoking Kills’ ²⁰ ) must be avoided. For cancer, knowledge dissemination both within the medical and lay ethnic community should focus on prevention through lifestyle and diet, and earlier detection through better awareness of symptoms and the need to seek medical advice early. If indeed the current low rates of cancer in ethnic groups such as South Asians are likely to increase with behavioural changes, then health protection targeting those behaviours should increase too.