Cancer cases rising; detection, reporting needed

Rates of cancer in Samoa have been increasing between 2007 and 2016 and better systems for detection and recording the disease are needed, a landmark study has revealed. 

The report titled: Cancer Incidence in Samoa: A 10-Year Retrospective Survey (2007-2016), was published last week in the Asia Pacific Journal of Public Health.

Unhealthy lifestyles are contributing to the rise in cancer rates, the report concludes, such as exposure to risk factors like obesity, consumption of tobacco and alcohol; infections and ageing are also identified as causal factors.

Women, the study found, were the group most affected by the rising incidence of cancer is almost twice as much in females than males. Women currently account for 62 per cent of all cancer cases in the country, while men 32 per cent. 

While cancer rates fluctuated under the period studied, a steady increase was recorded across the period. 

In 2007, 28.5 Samoans per 100,000 were diagnosed with cancer. By 2017 this figure had increased to 65.2, or more than double the earlier rate, despite some fluctuations in the years prior. 

The study is the first to include data from the Overseas Medical Treatment Office and Samoa Cancer Society that hosts cancer registries in Samoa.

The study calls for a national cancer registry that establishes clear lines of communication between pathologists and other sources of diagnostic information as a step toward improving cancer surveillance and research.

"This can provide basic but valuable information about cancer and other risk factors that overlap with other noncommunicable diseases among Samoan people," the report says. 

The high rates decrease in 2013 and 2015, with cancer incidence from 67.1 cases down to 51.4 cases per 100, 000 in 2013; another increase to 65.1 cases in 2014 and down again to 54.3 cases per 100 000 in 2015.

The study suggests the surge in incidences rates between 2009 and 2012 is a result of improved radiological diagnostics assisting with the screening of patients, after the receipt of a commuted tomography (or C.T.) scan from China.

Although the study notes the surge is partly the result of improved technology, it suggested the fluctuation in the year to year detection of cancers may be due to poor record keeping and documentation, the unavailability of diagnostic tests and equipment, or the absence of death certificates from medical notes.

“Other possible explanations include the unpredictable turnover of clinical staff, absence of diagnostic experts such as an in-country pathologist, and incomplete diagnostic reports from overseas centres where our patients are referred to for post surgery oncology treatments,” the study concludes.

“However, these results were consistent with previous findings across the world with the most cancer incidence to be the highest in the elderly population.”

For Samoa, despite slight changes in the trend of cancers over the past 10 years, cancer in the female genital organs including the uterus, cervix and ovary, breasts, and gastrointestinal organs remain the cancers affecting the greatest proportion of the population. 

Cancer incidence was highest in those older than 60 years in almost all types of cancers, except for breast cancer.

62 per cent of all cancer cases in Samoa are female, and 38 percent were males.

Among females, the top five cancers include female genitalia (36 per cent); breast (24 per cent); ill-defined, secondary, unspecified sites (9 per cent); digestive organs (8 per cent); melanoma and skin neoplasms (5 per cent); and lymphoid and hematopoietic (5 per cent).

Infection-related cancers, such as cancer of the stomach, appear to be very high among Samoan men compared with other Pacific countries.

And although breast cancer incidence rate in Samoa is high, the study notes that it is in fact, lower compared with neighbouring Pacific island states.

But cervical cancer rates have increased dramatically compared with the past eight years, the study noted. But these rates are still lower than in most Pacific nations such as Fiji, Vanuatu, and Papua New Guinea.

The top five cancers among males include digestive (21 per cent); melanoma and skin neoplasms (17 per cent); ill-defined, secondary, unspecified sites (12 per cent); lymphoid and hematopoietic (11 per cent) and male genitalia (10 per cent).

Meanwhile, Samoa has the lowest incidence rate of liver cancer among the men population compared with most Pacific countries including Fiji, Vanuatu, French Polynesia, and Papua New Guinea.

The report also noted that despite a general belief that people with naturally darker skin were at less risk of skin cancer, rates of skin cancer in the country were significant.

The study suggests its high incidence could be attributed to risk factors such as sun exposure, chronic inflammation, ageing, and an increase in the diversity of the Samoan population ethnicity.

More importantly, the significantly high rates of cancer where the primary site is not known reflects the poor quality and limitations of diagnostic services and weak cancer surveillance systems in Samoa.

The higher rates also reflect the poor health seeking behaviour of Samoans. Most cancer patients presented to doctors too late and would often refuse robust procedures for diagnosis.

The co-authors call for the need for population-based cancer registries to be established as well as death registration to be strengthened, saying the “huge disparity” across the data sources and analyses available for Samoa is “compelling” evidence.

“The relatively lower incidence rates of cancers reported in low- and middle-income countries including the Pacific Island Countries compared with high-income countries are partly due to the limitations in diagnostic capacity, underreporting, and incomplete cancer registration,” the study reads.

“These registries can provide the most reliable source of cancer information that health leaders have to depend on for cancer surveillance at a regional or national level.”

The co-authors recommend for national cancer control programs to be tailored specially to target at least the top 3 cancers focusing on female-specific cancers such as breast, uterus, and cervix because of their higher incidence rates.

“Cancer screening programs must target those older than 40 years since incidence for most cancers increases dramatically past this age according to our findings,” the study reads.

“Controlling certain risk factors, such as smoking, harmful use of alcohol, unhealthy diet, lack of physical activity, overweight, and obesity will decrease the incidence and burden of both cancers and other noncommunicable diseases that are afflicting not only Samoans but other Pacific countries.”

The report noted a lack of proper follow-up systems in place for cancer patients being referred overseas for treatment.

“Samoan patients are referred to New Zealand and India for post surgery oncology treatment, and there is no proper system in place for the [Health] Ministry to monitor diagnostic information for these patients,” the co-authors write.

“Hence, the more reason why national cancer control strategies as well national cancer registration must be strengthened.

“With these findings, provision of oncology treatment locally for common cancers with favourable responses and establishment of a palliative care unit can be justified and implemented in order to improve the quality of care for Samoans.”

The study was co-authored by Samoan, Filipina Amosa-Lei Sam; Ayodele Akinremi of Fiji National University; Les Mery of International Agency for Research on Cancer, France; Diana Sarfati, James Stanley and Jason Gurney of the University of Otago, New Zealand.

The study’s conclusions were based from an analysis of 836 cases of cancer records obtained from laboratory registers.