Extremes of temperature have been put to use in medicine for decades. In electro-coagulation, heat is used to seal blood vessels during surgery in order to stop bleeding. An organ for transplantation is kept at 4⁰C in order to prolong its viability so that it can be transported to distant places for its eventual implantation. More recently, in the field of oncology, excessive heat or cold is used to destroy tumours. In the media, much has been written about radiofrequency destruction of tumours. In radiofrequency, heat is generated by passing electrical current through a special probe inserted into the tumour; the heat generated ‘cooks’ the tumour. The machine generating the heat is relatively cheap and small in size. It is easy to use and as such has become a very popular mode of treatment not only in oncology but also in other medical fields. Cryoablation is the complete opposite to radiofrequency ablation; the destruction of tissue / tumour is by freezing. Although cryoablation has been around for a much longer time than radiofrequency , it is less popular than radiofrequency ablation. The old technology involves passing liquid nitrogen through a probe placed in the tumour. This creates an ice ball and when the freezing is complete, you wait until the probe ‘warms up’ before it can be removed. The size of the probe is relatively big and overall the whole set up is quite cumbersome and not convenient to use. Consequently, it did not gain widespread popularity. In the last 2 decades, cryoablation technology has come of age. With new technology, the freezing and thawing is achieved instantaneously by the passage of helium and argon gas through the probe, the probe size is very similar to that for radiofrequency ablation and thus cryoablation is now as easy as to use as radiofrequency. (The only downside is that it costs much more than radiofrequency ablation.)

At the recent 34^th Annual Scientific Meeting of the Society of Interventional Radiology in San Diego, doctors from the Johns Hopkins Hospital reported the efficacy data from 90 cryoablation procedures on 84 patients with renal tumours, size 1 – 10 cm, performed between April 2006 and December 2008. They reported that 88 tumours were treated completely without any evidence of recurrence. Patients with tumours that were ≤ 4cm were the ones with a 100% response. In a sub-group analysis, these patients remained free of disease at 2.5 years. In another presentation at the same meeting, a group from Orlando, Florida presented their data on treating prostate cancer by focal cryoablation. Instead of adopting the approaches of watchful waiting or treating the whole prostate with radiotherapy / surgery, these doctors perform focal cryoablation of the prostate gland to treat the underlying cancer. (The approach is analogous to lumpectomy, instead of mastectomy, for the treatment of breast cancer.) Of 120 men treated over a 12-year period, 93% (112 patients) of these men have stable PSA level and no evidence of cancer after a mean follow-up of 3.6 years. (Seventy two patients were considered at medium or high risk for recurrence.)

The new cryoablation technology may take a while to find its niche in the field of medical therapy. When radiofrequency technology came along, many wrote off cryotherapy. Indeed, at a recent medical symposium held in a local university in Kuching, Malaysia, that I was speaking at, the head of the department of surgery asked the panel of speakers if he should consider acquiring a cryotherapy machine for treating liver and other tumours. One of the speakers opined that it would be a waste of time and money as it is not as good as radiofrequency ablation. I was not as adamant. [I was fortunate to have had experience with both radiofrequency and cryotherapy (both old and new technology) in treating liver tumours. If we remove the cost issue, I am quite convinced that cryotherapy will have a definite place in treating certain types of tumours. It will complement other treatment modalities such as radiofrequency ablation. In the meantime, we just have to be patient and await more studies on cryotherapy to better define its rightful place in medicine.

Physical inactivity is associated with increased incidence of obesity, diabetes mellitus, cardiovascular diseases, osteoporosis and cancer. Consequently, the American Heart Association, the American College of Sports Medicine and the US Department of Health and Human Services recommended that adults engage in at least 30 minutes of moderate physical activity preferably on all days of the week. In a study, published in 2007, by the National Institute of Health, involving 252, 925 individuals, adherence to the above physical activity guidelines resulted in a 50% reduction in the overall mortality risk (Arch Intern Med 2007; 167: 2453 – 2460). Having been stuck in a sedentary lifestyle in one’s younger days, will increased exercise level later in life reduce one’s mortality rate?

Researchers from Uppsala University and Karolinska Institutet studied 2322 men aged 49 – 51 years at baseline and followed them up for more than 35 years (BMJ 2009; 338: b688). These men were studied again at ages 60, 70, 77 and 82 years. At baseline almost half of the men reported a high level of physical activity (at least 3 hours of recreational sports or heavy gardening a week), 36% reported medium activity (walk or cycle for pleasure) and 15% were sedentary (spending most of the time reading, watching TV and going to the cinema). The study found that the relative mortality rates were highest among sedentary men and lowest among the most active men. When converted into differences in remaining life expectancies from age 50, high physical activity men were expected to live 3.8 years longer than sedentary men and 1.8 years longer than medium physical activity men. Men who increased their physical activity to a high level at 50 and maintained it till age 60 had the same mortality rate as the men who had been at high physical activity before entering the trial. In other words, if you adopt a high physical activity lifestyle at 50, by the time you reach 60 you will have ‘caught up’ and have the same mortality rate as someone who has embraced a high physical activity lifestyle before 50 years of age. After > 10 years of follow-up, the mortality rate in men who had increased their physical activity to a high level both from a medium or low level had halved. After > 10 years of follow-up, compared to current smokers, smoking cessation was associated with a 40% reduction of mortality rate. Men who never smoked had a 60% lower mortality rate than current smokers.

To those middle aged men who smokes and exercise little, the excuse that ‘The damage is done. It is too late for me to stop smoking and start exercising.’ may seem a bit flimsy now. You might wish to heed the saying ‘It is never too late to try’. 

The World Cancer Research Fund (WCRF) and its sister organization, the American Institute for Cancer Research (AICR) in their recent report titled ‘Policy and Action for Cancer Prevention’ stated that approximately one third of common adult cancers in the US may be preventable. (This is not including those which can be prevented by not smoking.) The WCRF and AICR estimated that eating a nutritious diet, being physically active and keeping body fat under control may prevent:

• 38% of breast cancers
• 45% of colorectal cancers
• 36% of lung cancers
• 39% of pancreatic cancers
• 47% of stomach cancers
• 69% of esophageal cancers
• 63% of cancers of the mouth, pharynx, or larynx
• 70% of endometrial cancers
• 24% of kidney cancers
• 21% of gallbladder cancers
• 15% of liver cancers
• 11% of prostate cancers

According to the report, diet, physical activity and limited body fat could prevent 34% of these 12 cancers overall and 24% of all cancers.

A study from the Karolinska Institute followed 45,920 Swedish male conscripts from the period 1969 - 70 for 38 years and examined the effects of overweight in adolescence on subsequent adult mortality (BMJ 2009; 338: b496). Compared with normal weight [body mass index (BMI) 18.5 – 24.9 kg/sq.m] men, the mortality risk in overweight (BMI 25 – 29.9) and obese (BMI ≥ 30) men was increased by 33% and 114%, respectively. The risk was not increased in underweight men, but in those who were extremely underweight, BMI < 17, the risk of mortality was increased by 33%. The risk of mortality in light (1 – 10 cigarettes / day) and heavy (> 10 / day) smokers was also increased by 54% and 111%, respectively, when compared to non-smokers. (Since the start of this study the number of overweight adolescent men in Sweden has tripled and the number of those who are obese has increased 5 fold. Fortunately, the number of smokers has halved.)

Another study looked at the effects of alcohol consumption on the incidence of cancer risk in 1,280,296 women involved in The Million Women Study (J Natl Cancer Inst 2009; 101: 296 – 305). They attended breast cancer screening clinics in the United Kingdom from 1996 to 2001. The average follow-up time was 7.2 years. The 5 categories of alcohol intake were 0 (24%), up to 2 (29%), 3 – 6 (23%), 7 to 14 (19%) and at least 15 (5%) drinks of 10 g of alcohol (= 1 unit) / week. Increasing alcohol intake was associated with an increased risk of specific cancers. The excess cancer incidence of these cancers, up to 75 years of age, with 10 g increase in daily alcohol intake were:

• Oral cavity and pharynx – 1 per 1000
• Oesophagus – 0.7 per 1000
• Larynx – 0.7 per 1000
• Rectum – 1 per 1000
• Liver – 0.7 per 1000
• Breast – 11 per 1000

To put it another way, the researchers estimated that the background incidence of cancers among women in developed countries was 118 cancers diagnosed per 1000 women up to the age of 75 years. Drinking 1 unit per day increased this by an extra 15 cancers per 1000 women and 2 drinks a day  increased this an extra 30 cancers per 1000 women; the majority of the cancers would be breast cancer.

Most cancers are not inherited. For the small proportion of inherited cancers, your cancer risk is not within your control. For most of us, how you lead your life can impact on your cancer risk. Leading a healthy lifestyle does not reduce your cancer risk to zero; it does however reduce your odds of developing cancer. Do not think that regular health checks will save you from cancers. You hope that the checks will help you detect the cancer at an earlier stage, and that is no guarantee either. A healthy lifestyle has no downside. Embracing it might just save your life!