MetS has been recognized as an important secondary target for the prevention of cardiovascular diseases and diabetes , as well as reducing the mortality rate among cancer survivors . In this study, the Harmonized MetS definition that has been proposed in 2009 was used as a simple, useful and most updated guideline to diagnose MetS. Moreover, MetS prevalence was also reported by using WHO, ATP III and IDF diagnostic definitions for easier interpretation and comparison with other studies.
In this study, the prevalence of MetS among breast cancer survivors in East Coast of Peninsular Malaysia showed a higher percentage of subjects with MetS, up to half of the proportion of the investigated breast cancer survivors. When compared with the recent report by The Malaysian Breast Cancer Survivorship Cohort (MyBCC) study on the prevalence of MetS among newly-diagnosed breast cancer patients in UMMC, higher proportion of breast cancer survivors with MetS was reported in the current study (48.4%) compared to 37.8% in MyBCC study according to IDF 2005 definition . This difference can be attributed to the variation in breast cancer survival duration and ethnic composition percentage among the breast cancer survivors between these two studies. Furthermore, MetS prevalence among breast cancer survivors as reported in the current study was also similar, or higher than the data reported in other countries such as India – NCEP ATP III definition: 40.0% vs 40.0% respectively , China – Harmonized definition: 50.5% vs 32.6% , Korea – Harmonized definition: 50.5% vs 43.9% , USA – Harmonized: 50.5% vs 26.1% , Denmark – NCEP ATP III definition: 40.0% vs 15.1%  and Brazil – Harmonized definition: 50.5% vs 48.1%  respectively.
The higher proportion of breast cancer survivors with MetS in Asian countries as compared to Western countries reflected that MetS has become more prevalent in developing countries when compared to its Western counterparts due to increasing economic development in lower to middle-income countries [33, 34]. This transition is also closely linked to unhealthy lifestyle changes associated with modernization such as increased sedentary behaviour , changes in dietary practices  and mental health deterioration . As a result of increased mechanization and automation in daily activities in rural areas, there is also a rise in MetS prevalence in rural communities of the Asia-Pacific .
Contrarily, MetS prevalence among general women population had also been reported in numerous studies. In Malaysia, MetS prevalence among general Malaysian women in three nationwide studies were reported to range between 30.1% – 43.7% [15–17]. Besides, MetS prevalence among specific populations have also been reported, including among Kelantanese women (IDF definition: 32.2-36.6%) [38, 39], aborigines ‘Orang Asli’ women (Harmonized definition: 23.8%) , women in urban and rural areas (IDF definition: 10.8-39.3%) [41, 42], female university staff (NCEP ATP III definition: 21.4-45.3%) [43–45] and female government workers (Harmonized definition: 46.3%) . Comparatively, higher prevalence of MetS was observed among the breast cancer survivors than the general women population, which supported previous reports describing the tendency of breast cancer survivors to be diagnosed with MetS [4, 5]. Since there is large gap between prevalence of breast cancer survivors and national prevalence, this strengthen the theory that MetS in breast cancer survivor might not be related to age but due to pre-existing cardiometabolic risk factors and comorbidities at any point of their lives. However, evidence whether the cancer itself attenuates the risk of MetS is still scarce. On the other hand, a recent meta-analysis has shown that MetS may predict the risk of cancer recurrence and mortality in women with breast cancer, particularly in Caucasians .
In the present study, among those with MetS as according to the Harmonized MetS definition (≥ 3 criteria), more than half of them met three MetS components, whereas 31.3% and 16.6% met four and five components respectively. However, when compared among all breast cancer survivors included in this study, the percentage of women meeting two MetS components (25.3%) was almost similar to those meeting three MetS components (26.3%). Furthermore, studies conducted among adults in China , Thailand , Netherland  and Nepal  also reported an almost similar, or even higher percentage of adults with two MetS components. If left with no intervention, this group of breast cancer survivors that was just below the borderline of MetS diagnosis would have a higher tendency to have a worse health condition or even being diagnosed with MetS in the future. Particularly, breast cancer survivors have been reported to have higher weight after a cancer diagnosis as compared to a year before being diagnosed with breast cancer [53, 54].
Moreover, the most prevalent abnormal MetS parameters among all breast cancer survivors were abdominal obesity, followed by hyperglycemia and hypertension. Previous studies have also reported an almost similar trend of the top three most prevalent abnormal MetS parameters [50, 51, 55, 56]. As increased waist circumference has been reported to be closely related with excess adiposity, impaired insulin sensitivity and other cardiometabolic factors, incremental changes in waist circumference would have detrimental effects to other MetS components [57, 58]. Moreover, increased blood pressure was also associated with central body fat distribution, independent of BMI and insulin resistance . Meanwhile, dyslipidemia and hyperglycemia were more prevalent among breast cancer survivors with MetS. Therefore, targeting these conditions in the clinical settings should be the utmost priority in the effort to reduce MetS-related morbidity and mortality among breast cancer survivors in East Coast of Peninsular Malaysia.
Meanwhile, previous literatures have described the links between MetS and other sociodemographic and lifestyle factors among Malaysian adults, such as higher age, unemployment, working in shifts, postmenopausal status, living in urban area, lower socioeconomic status, Indian ethnicity, Chinese ethnicity and lower education level [6, 14–17, 38, 41, 60]. Specifically, these factors can be linked with other modifiable risk factors of MetS such as physical inactivity and unhealthy diets. According to Malaysian National Health and Morbidity Survey (NHMS) 2015, lower prevalence of physical activity was observed among older adults, Chinese ethnicity, those living in urban areas, having no formal education, retiree and lower household income . Additionally, other studies have also reported physical inactivity among Indian ethnicity . The NHMS 2015 survey also reported less intake of fruits and vegetables among Malays, those living in urban areas, having no formal education and middle-income group .
Similar to the findings of previous research, this study reported significant links between MetS and increased body weight [60, 62, 63], waist circumference [63–65], body fat percentage [63, 64] and BMI , except for total cholesterol level or LDL-c level. However, the findings revealed that MetS status is independent of sociodemographic and clinical characteristics. Older age, being Chinese ethnicity, being married, having low education level or being a housewife or pensioner is not a contributing factor for being at risk for MetS. Similarly, having a positive family history, having later or advanced cancer stage or longer duration of survivorship does not determine the risk of MetS. All other estrogen hormone related factors such as breastfeeding practices, being postmenopausal, oral contraceptive and hormone replacement therapy usage were not a significant risk factor for MetS as well among breast cancer survivors.
The differences in our findings may be attributed to several limitations of the study which should be addressed properly. Firstly, the breast cancer survivors included in this study were recruited only from Terengganu and Kelantan, hence the findings of this study might not represent all breast cancer survivors in Malaysia. Additionally, due to the sociodemographic characteristic and racial distribution of breast cancer survivors in Terengganu and Kelantan, data on breast cancer survivors from other ethnicities were very scarce, hence analysis on ethnicities and MetS in this study was very limited. It is also important to note the possibility that breast cancer survivors that agree to participate in this research might have more health-awareness compared to non-participants. Similarly, other important risk factors such as physical activity and dietary intake were not reported in this study. Therefore, the links and their confounding effects on MetS could not be determined.