Beware of what, you might enquire? The fact that I do not smoke means I am not going to have increased risk of blocked arteries, heart disease, emphysema and lung cancer. So, if I do not smoke, I am safe, right?

Researchers from the Roswell Park Cancer Institute in Buffalo, New York examined the age at diagnosis of colorectal cancer (CRC) of subjects exposed to tobacco smoke (J Cancer Res Clin Oncol; 2008 Feb 9 epub). Between 1957 and 1997, 3540 patients were treated for CRC at Roswell Park. Compared to non-smokers, current smokers demonstrated the youngest age of CRC onset. The average age at CRC diagnosis for current smokers was 57.4 years compared to 64.2 years for non-smokers. Ex-smokers, who quit smoking < 5 years earlier, also developed CRC at a younger age. These ex-smokers have CRC diagnosed 4.3 years younger than non-smokers. People who quit smoking > 5 years earlier had no significant increased risk. Smoking from early teens, before 17 years of age, and smoking ≥ 1 pack per day were most likely to be associated with CRC being diagnosed at a much younger age than in non-smokers. Passive smokers were also found to have CRC diagnosed at a younger age when compared to non-smokers. When active smokers and passive smokers were combined into 1 subgroup for analysis, the age at CRC diagnosis was nearly 10 years earlier than non-smokers. The authors of the study concluded that for persons with a lifetime history of tobacco smoke exposure, screening for CRC should be initiated 5 – 10 years earlier i.e. at age 40.

How smoking causes colon cancer is still unknown. As time goes on, the list of health hazards associated with smoking will no doubt grow longer. Even for non-smokers, their health can be adversely affected by being exposed to second-hand smoke. While smokers are exercising their right to smoke, non-smokers should be vocal about their right not to be exposed to second-hand smoke too. Unless of course you do not mind having an increased risk of developing CRC at an earlier age!

I recently attended a talk on prostate cancer and whether chemoprevention has a role to play. At the talk, the speaker concluded that at present we cannot prevent prostate cancer but recommended regular screening for prostate cancer with digital rectal examination (DRE) of the prostate gland and measurement of the prostate-specific antigen (PSA) level in the blood for all men above 50 years of age.

The most important argument for advocating cancer screening is to allow diagnosis at an early / earlier stage. This would allow earlier intervention which potentially would decrease morbidity and mortality. The principal screening tests for detecting asymptomatic prostate cancer are DRE and measurement of the level of the tumour marker, PSA.

After reviewing all the medical literature on prostate cancer screening published up to June 2007, the American College of Preventive Medicine (ACPM) published its findings and position statement on the matter in the American Journal of Preventive Medicine this month (Am J Prev Med 2008; 34: 164 – 170). The authors of the report wrote: The American College of Preventive Medicine concludes that there is insufficient evidence to recommend routine population screening with DRE or PSA. Clinicians caring for men, especially African-American men and those with positive family histories, should provide information about the potential benefits and risks of prostate cancer screening and the limitations of current evidence on screening in order to maximize informed decision making.

Apart from earlier detection, the potential benefits of screening include reassurance of being at low risk for prostate cancer. So, what is the potential harm of screening? Screening can give rise to false-positive and false-negative results. A false-negative result will give rise to false reassurance and can lead to a delay in the actual diagnosis of a prostate cancer. A false-positive result would lead to increased anxiety for the patient and family. The prostatic biopsy necessary to rule out the false-positive diagnosis can lead to complications such as pain, hematospermia (blood in the semen), haematuria (blood in the urine) or infection of the prostate. Some would argue that this is a small price to pay in order to be reassured.

How accurate are DRE and PSA level in detecting an underlying asymptomatic prostate cancer? In clinical studies, the sensitivity of DRE in detecting prostate cancer has been shown to be highly variable. The sensitivity varies from 18% to 68%. In the presence of a normal PSA level, the positive predictive value of DRE for prostate cancer is 4% to 33%. In epidemiologic studies, the positive predictive value of PSA levels for an underlying prostate cancer is approximately 30%. Although a PSA value of ≤ 4 ng/mL is widely accepted as normal, some physicians have suggested a lower cutoff value in order to improve test sensitivity. Other PSA tests have been suggested in order to improve the sensitivity and specificity of PSA as a tumour marker. Age-specific PSA has been used to increase the test sensitivity but this is being achieved at the cost of reduced specificity (meaning you can get more false-positive). Another test which improves detection sensitivity is monitoring the rate of change of PSA with time, called PSA velocity, whereby an annual PSA increase of 0.5 ng/mL or 0.75 ng/mL have been advocated as ‘normal’ values. Measuring free PSA level is another approach to improve specificity of prostate cancer screening. The percentage of bound PSA is higher among men with prostate cancer versus those with benign disease. However, there is no agreement on the optimal cutoff value for free PSA values.

What do other learned medical bodies recommend? The American Urological Association recommends that men who are 50 years and older and who have an estimated life expectancy of more than 10 years should be offered PSA screening. The American Cancer Society recommends that men who are 50 years and older and who have a life expectancy of more than 10 years should be offered both DRE and PSA screening. The United States Preventive Service Task Force and American Academy of Family Physicians do not find sufficient evidence for or against PSA or DRE screening. The Canadian Task Force on Preventive Health Care recommends against routine screening with PSA.

At present, according to the American Cancer Society, no major scientific or medical organization supports routine testing for prostate cancer. So, what should the over 50, average risk, male population do? Until the results of the 2 ongoing randomised controlled trials on prostate cancer screening have been published, the patient should be given information on the limitations of current evidence on screening and on the pros and cons of prostate cancer screening, so that he can make an informed decision on screening. Yay or Nay, it is your call.

Infants and toddlers receive various immunizations in their early life. Most if not all are painful when administered. In USA, the 2006 immunization schedule requires infants to receive as many as 24 injections in their first 2 years of life and as many as 5 injections at a single visit. While immunizations are beneficial to future health, some parents are reluctant to adhere to the immunization schedule partly because of their perception that their children have to endure a substantial amount of pain during routine immunizations. The long-term effects of unmanaged pain in human infants have been shown to include permanent impairment of elements of cognitive development, such as learning, memory and behaviour. Early painful experiences will affect children’s future perceptions of and response to pain later in life. Thus, any simple manoeuvres which can help to reduce the pain experienced during immunizations will hopefully modify the infant’s response to pain later in life.

A recent study from the Pennsylvania State University examined the analgesic efficacy of giving oral sucrose to infants during routine immunizations (Pediatrics 2008; 121: e327 – e334). One hundred healthy infants scheduled to be immunized at 2 and 4 months of age were studied. The infants were randomly assigned to receive oral sucrose or placebo (sterile water) onto the surface of the tongue followed immediately by the insertion of a pacifier into the mouth. The pacifier was held in place by the parent or the clinic nurse 2 minutes before, during and 7 minutes after the initial immunization. The vaccines used were a combined diphtheria, tetanus, acellular pertussis, hepatitis B and polio vaccine; a Haemophilus influenza type B vaccine and a heptavalent pneumococcal conjugate vaccine. The vaccines were administered consecutively. The study showed that the pain score for those infants who received oral sucrose was significantly lower than for those who were given sterile water. In the sucrose group, the behavioural pain response score exceeded 2 at 5 minutes (after the second of the 3 injections). In the placebo group, the score exceeded 3 at 2 minutes (after the first of the 3 injections, see figure).

It is understandable that parents feel pain when they witness their baby cry in response to an injection. However, it would be a pity if parents skipped some of the immunizations because they wanted to spare their baby the pain of being injected. Now that they know there is a simple manoeuvre that, when adopted, can significantly reduce the pain and discomfort experienced by the baby, hopefully parents will have less compulsion to skip some of the immunizations for their baby.