Modelling of survival and incidence for colorectal cancer in Malaysia
Creators: name: Ghazali, Anis Kausar
Publisher: name: Lancaster University
Year: 2018

description: Colorectal cancer is the third most common cancer worldwide, with an
      estimated 1.36 million new cases and 694,000 deaths recorded in 2012. This
      number is expected to increase by 80% reaching approximately 2.4 million
      cases in 2035, and contributing to 1.3 million deaths globally per year. 
      
      
      In Malaysia, colorectal cancer is the second most common cancer, in both
      men and women, behind lung cancer in men and breast cancer in women
      respectively. The most recent estimate gives the incidence of colorectal
      cancer in Malaysia as 21.3 cases per 100,000 population and 9.8 deaths per
      100,000 population for the six years period reported between 2008 and
      2013. 
      
      
      The incidence of colorectal cancer is known to vary by place and by time
      period. However, most research on the spatial and variation in cancer
      incidence has taken place outside South East Asia, and such research on
      this is still scarce in Malaysia. The research presented in this thesis
      investigates individual factors affecting survival, and the spatial
      variation in incidence and survival of colorectal cancer in Malaysia. This
      has not been done before in Malaysia.
      
      
      There are three objectives addressed in this thesis: (1) to investigate
      the individual characteristics that affect survival of colorectal cancer
      in Malaysia, (2) to investigate and model the spatial variation of
      survival in colorectal cancer in Malaysia, (3) to investigate and model
      the spatial variation in the incidence of colorectal cancer in Malaysia.
      
      
      The research was involved 4412 of colorectal cancer patients in Malaysia
      with histologically verified primary colorectal cancer who were diagnosed
      between 2008 and 2013 (ICD-10, C18-C20), recorded in the database of
      National Cancer Patient Registry- Colorectal Cancer (NCPR-CC) Malaysia. We
      investigated the effect of individual characteristics such as age, gender,
      education as well as clinical characteristics such as cancer staging,
      cancer site and treatment modalities on survival prognosis after a
      diagnosis of colorectal cancer using a Cox regression model. The analysis
      was then been extended to model the spatial variation in survival for
      colorectal cancer patients in Malaysia, accounting for individual and
      socioeconomic characteristics using a spatial survival model. We then
      applied a Generalized Linear Mixed Effects model, which is derived from
      the log-Gaussian Cox Process, in order to model the incidence of
      colorectal cancer in Peninsular Malaysia.
      
      
      Our findings show that the severity of disease at diagnosis as measured by
      cancer staging, tumour grading and the presence of distant metastases,
      plays an important role in the prognosis of patients with colorectal
      cancer in Malaysia, and that this remains even after controlling for
      spatial correlation on space. Our research allows us to shows the
      geographical variation in survival of colorectal cancer in Malaysia, and
      what variation persists once individual and socioeconomic characteristics
      are taken into account.
      
      
      Our model that developed to predict the colorectal cancer incidence found
      that that some places had greater risk of an incidence exceeding the
      national average. The map for probability of exceedance relative risk of
      colorectal cancer incidence in the North West of  Peninsular Malaysia
      shows variation in the risk for colorectal cancer cases across the region.
      We noted that town areas are highly likely to exceed the threshold of
      relative risk of increased number of colorectal cancer cases, and this
      effect is present even though we account for the additional population
      there.
      
      
      Spatial variation in survival and incidence of colorectal cancer in
      Malaysia needs to be investigated further. To the best of our knowledge,
      this is the first research that uses spatial modelling to identify
      potential factors affecting the incidence and survival for colorectal
      cancer in Malaysia, as well as to map the risks in survival and incidence.
      Our findings can help public health authorities to plan better management
      of the resources used to prevent and treat this disease.