Being obese is known to be associated with increased health problems. These include diabetes, heart diseases, sleep apnoea and joint problems to name a few. It is also known that obese women have an increased risk of breast cancer. Is this association true for other cancers too?

Researchers from several universities from both sides of the Atlantic analysed the pooled data from the National Cancer Institute Pancreatic Cancer Cohort Consortium (PanScan) to look at possible association between obesity and risk of pancreatic cancer. The study included 2170 cases of pancreatic cancer and 2209 controls (Arch Intern Med 2010; 170: 791 – 802). They recorded body mass index (BMI) [< 18.5 underweight, 18.5 – 24.9 normal weight, 25.0 – 29.9 overweight, 30.0 – 34.9 obese and 35.0 severely obese], waist circumference and waist to hip ratio. In men, the risk of pancreatic cancer in those with the highest quartile of BMI is increased by 33% as compared to those with the lowest quartile BMI. In women the increased risk is 34%. An increased waist to hip ratio, between the highest and lowest quartile, was also associated with an 87% increased risk of pancreatic cancer in women.

We have two types of cholesterol in our body: ‘good’ cholesterol, namely high-density lipoprotein cholesterol (HDL-C), and ‘bad’ cholesterol called low-density lipoprotein cholesterol (LDL-C). We know that people with adequate levels of HDL-C are protected from heart disease. Does having more good cholesterol also protect you from cancer?

Researchers from Tufts University in Boston, USA, examined the relationship between HDL-C levels and the risk of developing cancer in 24 large randomised controlled trials (RCTs) of lipid-altering interventions (J Am Coll Cardiol 2010; 55: 2846 – 2854). The study found that there was a significant inverse association between baseline HDL-C levels and the rate of incident cancer. In other words, the higher the HDL-C level, the lower is the risk of cancer. After controlling for variables such as LDL-C level, age, BMI, sex and smoking status, the study found that for every 10 mg/dL increase in HDL-cholesterol, there is a 36% lower risk of developing cancer.

Most individuals put on weight because they eat more than they need. Whether you manage to lose weight or not depends on your motivation and determination. Participants in the reality show ‘The Biggest Loser’ manage to lose significant amounts of weight because they are being motivated to do so. Not everyone will get the chance to go on the show in order to be motivated. However, is the knowledge that becoming obese will increase your risk of developing cancer not enough to motivate you to keep trim?

Residents of a condominium or housing estate in Singapore scurry to close all their windows when they hear “Brrrrrr ….” outside their flat or house. This is the familiar sound of the machine which spews out a thick cloud of insecticide to kill mosquitoes or bugs in the compound. When the dense white cloud has dispersed, the air is still laced with the lingering smell of chemicals for some time. I have always wondered what health hazard this fogging / fumigation poses.

A recent article titled “Residential and childhood leukemia: A systematic review and meta-analysis” written by researchers from the University of Ottawa caught my eye (Environmental Health Perspectives 2010; 118: 33 – 41). They reviewed and analysed previously published epidemiological studies examining the relationship between residential pesticide exposure during critical exposure time windows (preconception, pregnancy and childhood) and childhood leukaemia. The analysis found a positive association of exposure and childhood leukaemia. During pregnancy, exposure to unspecified residential pesticides, insecticides and herbicides carried 54%, 105% and 61% increased risk of childhood leukaemia, respectively. During childhood, exposure to unspecified residential pesticides and insecticides carried 38% and 61% increased risk of childhood leukaemia, respectively.

Most childhood leukaemia occurs in the first few years of life. Most leukaemics carry gross chromosomal abnormalities in their blood. A study in the late 90s on routinely collected blood samples in neonates showed the presence of leukaemic clones with specific chromosomal translocations in children who later developed acute lymphoblastic leukaemia (ALL) [Proc Natl Acad Sci USA 1997; 94: 13950 -13954]. Another study suggested that pre-leukaemic clones may persist throughout childhood and may require post-natal exposure for leukaemic progression (Genes Chromosomes Cancer 2004; 39: 335 – 340). A recent study of infants born in an agricultural region in the Philippines showed that the prevalence of a common acute myologenous leukaemia (AML) translocation [t(8;21)] in cord blood samples was about doubled in those infants with detectable meconium levels of the methylcarbamate insecticide propoxur (Pediatr Blood Cancer 2007; 49: 624 – 628).

Leukaemia is the most common form of childhood cancer in Canada and the United States. ALL accounts for about 80% of childhood leukaemic cases. The next most common is AML. Although the precise mechanism on how leukaemia develops is still unclear, the two-step leukaemia model proposes that leukaemia development occurs after 2 mutations. The first mutation, usually a chromosomal translocation, occurs in utero. The second mutation, occurring after birth, completes the process and leukaemia occurs. While ionizing radiation is the only proven environmental risk factor to play a role in the etiology of leukaemia, other potential risk factors include parental smoking and alcohol consumption, electromagnetic field exposure, hydrocarbons, socioeconomic factors, immunity and infection and pesticides.

While it has not been convincingly proven that pesticides / insecticides cause leukaemia, it is probably no harm that we avoid unnecessary exposure to these substances as much as possible. While fogging / fumigation helps to reduce the mosquito population, it may bring nastier problems in its place to you and your family.

Does the statement “The will to live” refer to a proven scientific phenomenon or is it an abstract concept without scientific basis? Does “The will to live” refer to an internal switch which an individual can just ‘switch off’ at will and thus ending one’s life? Let me recount a recent event and you can be the judge.

I was recently looking after a very pleasant, elderly gentleman with inoperable hepatocellular carcinoma (primary liver cancer). During the course of his illness, he suffered the complications of ascites (fluid in the abdomen) and oesophageal variceal bleed (bleeding from a vein in the oesophagus). His liver function started to deteriorate and he became jaundiced. Despite all this, he remained cheerful, co-operative and stoic while being nursed at home. On my visits, he was always upbeat and promised to soldier on and ‘do what the doctor has advised’. This went on for about 3 weeks.

One Saturday, out of the blue, the gentleman casually said to his daughter-in-law “I am getting tired of fighting”. The weekend passed as per usual. Sometime on the Monday morning, the gentleman said to his daughter-in-law “I am leaving tomorrow”. By the time the daughter returned from work on the Monday evening, the gentleman was not responding to her speech. Although he was awake, he did not speak or ask for food / water. In the early hours of the Tuesday morning I received a call to say that he had had a brief episode of breathing difficulty but it had settled. As the children were concerned, I arranged for his admission. When I saw him, he was comfortable and breathing normally. His eyes were open but he did not respond to me. I admitted him and kept him comfortable. Early on Tuesday afternoon, several hours after admission, he passed away peacefully.

The children asked “How did he know?”; “Could he just switch off like that?”  I do not have the answers. Have I seen such an incident before? Yes, on many occasions. Do I have a scientific explanation for it? No.

Examples of the will to survive are not uncommon in the animal kingdom. I believe we humans possess the same innate power to want to survive. In the animal kingdom, some animals can sense that their time has come. Perhaps our ‘sense’ is not as developed as in animals.

In a similar vein, I have noticed that a patient’s mental attitude towards illness plays a role in his / her recovery. A patient who goes into an operation with a positive mental attitude tends to have a much smoother post-operative recovery. Patients who have an indifferent or negative attitude somehow have a more choppy recovery. I do not have a scientific explanation for these “abstract phenomena” and I am not perturbed by it. I see these as reminders that there are still things that we, the scientific community, do not understand and cannot explain. That is the wonder of life!