The rising cancer burden in Asia
The burden of cancer care worldwide is expected to increase in the next decade and beyond. With population growth, ageing and risk factors, the estimates by bodies such as the World Health Organisation (WHO) suggest that cancer deaths will increase by 45
Although ageing as a risk factor cannot be altered, certain lifestyle factors and infections are amenable to change with the potential to impact on this rising incidence. Tobacco use is the most important risk factor and infections ranging from hepatitis to human papilloma virus (HPV) contribute significantly to this rising epidemic. It is worthy to note that vaccinations are available for hepatitis B and HPV nowadays. Alcohol consumption is another risk factor and is commonly associated with lifestyles that include smoking. It is not uncommon that patients present in the later stages of disease and especially in lower income countries, access to diagnostic services and care may be less available. With Asia’s population poised to constitute about half of the world’s population, the impact of cancer in Asia will have major implications on the health and economies of the countries affected. Types of cancer in males that are predicted to predominate would include: lung, stomach, liver, colorectal, oesophagus, prostate and bladder. In females, these would include: breast, cervical, lung, stomach, colorectal, liver and uterine.
For decades, treatment paradigms have been driven principally by research and data derived from Western populations. However, with the rising awareness of the need to derive more Asian-centric data, more efforts have been made by researchers and pharmaceutical companies to invest in this facet of research. The much-quoted illustration of how lung cancer types differ between Caucasian populations
and East Asians is a case in point. The development of drugs that target the Epidermal Growth Factor Receptor (EGFR) in lung cancer did not see much benefit in a predominantly Caucasian population. It was the subsequent finding of a higher incidence of non-smoking related lung cancer in East Asians who were then found to have a higher prevalence of EGFR mutations, that culminated in studies that showed much more benefit for this specific group of patients who received this class of drug. The recognition that lung cancer types vary significantly has led to further exploration of various driver mutations for this cancer, with further success in identifying other subsets which now can benefit from specific targeted drugs.
Research into issues pertaining to drug metabolism and in particular the differences between Western populations and Asians has also led to a better understanding of the rationale for recommending different doses and schedules for patients. Examples range from higher toxicities from lower clearance of Docetaxel in East Asians to better tolerance of oral Capecitabine in East Asians as compared with Caucasians. Hence, the old paradigm of determining treatment guidelines solely based on Western hemisphere derived data is gradually shifting, with greater awareness of the need to conduct well-planned studies in Asian populations.
Notwithstanding the differences between ethnicities, many of the key clinical trials that have been conducted in the international arena have helped shape the exciting breakthroughs in cancer therapy. Inclusion of many Asian centres in these studies have helped ensure confidence in the findings that can therefore be applied locally. Overall, the investment in science is reaping dividends with patients benefiting. From an improvement in understanding cell cycle kinetics, to appreciating how blood vessel growth is an essential part of a malignant tumour’s growth, to identifying oncogenic driver mutations that are the main growth impetus in select cancers and to unlocking inhibitory signals on immune cells, these examples of “bench” work have now given rise to actual therapeutic molecules and drugs literally and figuratively at the “bedside”. Headlines in the media have heralded a newer age of therapeutics whereby multiple facets of cancer growth can be targeted beyond the traditional chemotherapy drugs. Hence the coining of “targeted therapy” has been an apt description of these newer novel therapies.
Options for treatment would also include surgery and radiation therapy, with the former a key consideration for the aims of curative treatment in early stage cancer. We have also seen advances in these disciplines that frequently combine science with engineering ingenuity. Laparoscopic (“keyhole”) surgery is now a mainstay for many standard procedures, with equivalent results but less morbidity and quicker recovery as compared with traditional “open” surgery. The classic sight of a surgeon postured over a patient has changed to one where there is manipulation of instruments from outside the patient’s body, guided by the images on a video
Robotic surgery where the surgeon sits and utilises the unique agility of mechanical arms especially in narrow or confined regions of the body, can allow for less traumatic resections of tumours. Radiotherapy options have also progressed with greater precision and the ability to plan treatments to conform to the shape and volume of cancers, which often grow in asymmetrical ways to give rise to different shapes. Such focussed therapy has helped not just deliver more precise doses but also minimises effects to surrounding tissue. Computer systems and software are now also able to coordinate the timing of radiation in accordance to a patient’s breathing to also further minimise doses to normal tissue.
The ability to understand the nature and extent of a cancer issue is of great importance in determining the most appropriate treatment plan. Diagnostic and imaging studies have a role which cannot be understated. Just as with how innovation has led to improved treatments, we have also seen how newer scanning technologies and more accurate diagnostic capabilities greatly benefit patients and families. The traditional manner of performing a biopsy of the prostate by the urologist may give way to a more precise MRI guided approach as recently demonstrated. And to aid the pathologist in determining the diagnosis and type of malignant cell, techniques range from simple stains to genetic analyses. Prognostic and predictive tests and panels are often considered to help in treatment decisions and the advent of exome sequencing on multi-gene panels to search for an array of genetic mutations has altered the approach for diagnosis and treatment selection.
However, much as the armamentarium for treatment has greatly improved, certain challenges remain for Asian countries. The wide variance in development of each country or region, coupled with differing economic strengths, governance and healthcare capabilities means that there remains an immense difference in access to diagnosis and care for patients. Each healthcare system is modelled differently with different payment or reimbursement systems, and the heterogeneity of populations makes for varying risks of types of cancer and their presentations.
Screening programmes to detect pre-malignant changes or early stage cancer have received inadequate attention and focus at national levels for most countries. A resounding concern of late has been the question of managing healthcare costs, which has seen expenditure from governments, third party payers and patients rise significantly.
In Singapore, the Agency for Care Effectiveness (ACE) has been established by the Ministry of Health to help drive clinically effective and cost-effective patient care, following the lead of other countries such as the United Kingdom’s National Institute for Health and Care Excellence (NICE). All these challenges should not be insurmountable, but will pose obstacles to providing equitable, state-of-the-art yet cost-effective cancer care for Asians.