Deprivation Gap in Both Cancer Incidence and Treatment

Liam Davenport

November 05, 2020

There is a clear deprivation gap in the incidence of cancer in England for a number of cancer types that appears to point to differences in the prevalence of risk factors such as smoking, and the uptake of screening, suggests data from two Cancer Research UK analyses.

Moreover, people from low socioeconomic backgrounds are less likely to have access to the latest targeted and precision cancer therapies than those from more affluent backgrounds, particularly for those with lung cancer, indicates a meta-analysis.

The research was presented at the National Cancer Research Institute (NCRI) Virtual Showcase 2020 on November 2.

Deprivation Data 

In the first of two studies he presented at the meeting, Nick Payne, from the Cancer Intelligence Team, Cancer Research UK, said that England is the only country in the UK that does not routinely provide an update of cancer incidence by deprivation.

Consequently, the most recent data is "outdated".

The team therefore gathered cancer incidence from Public Health England for the years 2013–2017, and the Office for National Statistics provided population estimates for the same period.

The data were stratified by sex, 5-year age band and quintiles of the income domain of the Index of Multiple Deprivation, and compared with age-standardised cancer incidence rates from the 2013 European Standard Population.

The results showed that, in the most deprived quintile, there were more cases of primary lung cancer, cancer of unknown primary, head and neck cancer, stomach cancer, and oesophageal cancer than in the least deprived quintile.

This totalled an excess of approximately 27,000 more cases of cancer per year in England.

In contrast, people in the most deprived quintile were also found to have fewer cases of skin melanoma, prostate cancer and female breast cancer, among others, giving 10,700 fewer of these cancer cases per year in England.

This indicated that individuals in the most deprived quintile had an overall excess of all cancer cases combined of approximately 16,800 per year in England.

"The reasons behind this are complex and multifaceted," Payne said in his presentation. "However, we believe that risk factors and screening behaviour are playing an influential role."

He said that, for cancer types that are positively associated with deprivation, contributing factors are likely to include smoking and overweight and obesity.

"This is because both of these risk factors are positively associated with deprivation, and [they] have a large number of cancer types associated with them that are also positively associated with deprivation."

Affluence Risks

Nick Payne told Medscape News UK that the inverse association with deprivation in the case of skin melanoma is likely to be because "more affluent people are more likely to go to sunnier destinations".

For female breast cancer, where the incidence is also higher in less deprived populations, "screening is also implicated", he said.

It is known that women from more affluent backgrounds "are more likely to attend their breast cancer screening programme, and we also know that women from more deprived populations are more likely to experience barriers to get in to screening in the first place," including language barriers.

"Obviously the screening is doing its job and working well but it’s further highlighting the inequalities because it’s working well for less deprived populations but it’s not reaching...those from more deprived populations," Payne said.

“Women in the least deprived quintile are also more likely to use post-menopausal hormone replacement, and to have fewer children and have them later, than those in the most deprived quintiles, and these are known risk factors for breast cancer.” Payne continued.

In the case of prostate cancer, there may not be a national screening programme, but it is known that "more affluent populations are more likely to seek out" prostate specific antigen testing, Payne said.

"So that obviously leads to higher diagnoses of prostate cancers."

Smoking Data

For the second study, Payne and colleagues combined the cancer incidence data and population estimates from the first study with smoking prevalence rates for the years 2003-2007 from Health Survey England.

The results showed that the proportion of smoking attributable cancer cases was strongly related to deprivation.

The population attributable fraction in the least deprived quintile was 12% in men and 8% in women, compared with 25% in men and 17% in women in the most deprived quintile.

Notably, it appears from other data that the deprivation gap in cancer cases attributable to smoking is widening over time.

Payne told Medscape News UK that this is because, while the "overall smoking prevalence has declined, which is good", the decline has primarily been in less deprived populations, and "the rate of decline in more deprived populations is nowhere near the same".

He continued: "Lung cancer in particular is the main driver of these excess cases that we’re seeing, [as] smoking and deprivation are entangled."

Inequalities

Presenting the third study, simultaneously published in BMC Medicine, Ruth Norris, a PhD candidate at the Population Health Sciences Institute, Newcastle University, said it has long been the case that there are inequalities in cancer treatment utilisation.

These socioeconomic inequalities in accessing chemotherapy, surgery, and radiotherapy have been seen across all cancers and healthcare systems, and have persisted over time.

She also noted that the latest systemic treatments, such as tyrosine kinase inhibitors and monoclonal antibodies, are "expensive" and require patient stratification with molecular pathology testing to predict the tumour response and hence who should receive them.

To examine whether these novel therapies and their predictive biomarker tests are affected by socioeconomic inequalities, the researchers conducted a systematic review of the MEDLINE, Embase, Scopus, CINAHL, Web of Science, PubMed and PsycINFO databases.

They selected peer-reviewed studies published in English between 1988 and 2019, performing a meta-analysis by cancer site and drug class.

Of 58 studies, 42 from the USA, included in the analysis, eight reported utilisation of predictive biomarker tests, 37 utilisation of biological and precision therapies, and three of both tests and treatments.

These concerned seven cancers, five predictive biomarker tests and 11 biological and precision therapies, the most common of which were bevacizumab and trastuzumab.

The results showed that low socioeconomic status was associated with a modest reduction in the utilisation of predictive biomarker tests, at an odds ratio of 0.86 (p=0.14).

When it came to biological and precision therapies, utilisation was significantly associated with low socioeconomic status, at an overall odds ratio of 0.83, with a stronger association seen for immunotherapy, at an odds ratio of 0.82.

The effect was also stronger in patients with lung cancer, at an odds ratio of 0.71, and was less marked for breast cancer, at an odds ratio of 0.93.

In her presentation, Norris said: "We’re not really sure why" the association varies by cancer type.

"Factors such as multimorbidity, and the social determinants of health could be playing a role, but so too could the length of time that receptor subtyping and treatment differentiation has been in practice."

She explained that, "over time, treatment access could trickle down and become standard clinical practice, and disparities could narrow".

In any case, Dr Norris said that more UK analyses are needed to "be sure this isn’t just an American issue".

The studies by Payne and colleagues were funded by Cancer Research UK.

The study by Norris and colleagues was funded by a Barbour Foundation PhD Studentship.

No relevant financial relationships declared.

NCRI Virtual Showcase 2020: Abstract: Cancer Incidence by Deprivation in England, 2013-2017. Presented November 2.

NCRI Virtual Showcase 2020: Abstract: The Fraction of Cancer Attributable to Smoking by Deprivation in England, 2013-2017. Presented November 2.

NCRI Virtual Showcase 2020: Abstract: Are there socio-economic inequalities in utilisation of predictive biomarker tests and biological and precision therapies for cancer? A systematic review and meta-analysis. Presented November 2.

Norris et al. BMC Medicine 2020; 18:282 doi: 10.1186/s12916-020-01753-0

NCRI Virtual Showcase 2020: Abstract: The impact of ethnicity on breast cancer surgery decisions and mortality in England: a population-based cohort study. Presented November 2.

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