Colorectal cancer is the second most common cancer in the world. The most common site for cancer spread is to the lymph nodes around the colon cancer. Once the spread has gone beyond the lymph nodes, the most common site for the colon cancer cells to lodge and grow within the body is the liver.

Colon cancer deposits in the liver are called colorectal liver metastases (CLM). It is estimated that about 50% of patients with colorectal cancer will develop CLM at some point in time. These liver metastases are usually detected by performing an ultrasound scan (USS) or a CT scan of the liver. The treatment options available to these patients are liver resection for cure or palliation with chemotherapy. For those patients with inoperable CLM the treatment is chemotherapy. In a proportion of patients, the chemotherapy treatment can cause one or more of the liver lesions to shrink and even ‘disappear’ on subsequent CT scans. When the lesion disappears, some oncologists and patients consider this as a sign of cure, but is it?

When liver metastases disappear on CT scanning, it is termed a complete radiological response (cRR) to chemotherapy. However, what is not entirely clear is that when a liver metastasis is completely invisible on CT scan, does it mean that there will be no viable cancer cells present when the previously affected site is examined under the microscope? The complete disappearance of cancer cells in the previously affected site following chemotherapy is called complete pathological response (cPR). There is only one way for doctors to determine cPR and that is to remove the affected site and submit it to microscopic examination by a pathologist.

What is the significance of a cPR over a cRR? When a lesion shows cPR there are no viable cancer cells present and the cancer is unable to ‘re-appear’ in that site. In cRR there are possible viable cancer cells and given time these dormant cancer cells will grow. Eventually this collection of cancer cells will become visible CLM again on subsequent CT scans.

A recent publication from France titled “Complete response of colorectal liver metastases after chemotherapy: Does it mean cure?” (J Clin Oncol 2006; 24: 3939 – 3945) looked at this issue specifically. In the study, systemic chemotherapy managed to cause 66 of 183 CLM (36%) to disappear on CT and trans-abdominal USS scanning. Before surgery, 20 CLM in 9 patients had cRR demonstrated on scanning. However, at the time of surgery, USS of the liver showed that these 20 CLM had not completely disappeared and were indeed still present. In 15 patients who had cRR, the previously affected liver was examined with USS during surgery to confirm that the CLM was truly not visible. The liver surgeon went ahead and removed the previously affected region of the liver and subjected it to microscopic examination. In 80% of the cases, the previously affected area contained live cancer cells. In another group of patients who together had 31 CLM showing cRR, the surgeons at operation only performed USS of the liver to confirm that these CLM were truly not visible. These affected areas of the liver were left alone. After one year of observation, 74% of these ‘cured’ areas had cancer recurrence and became visible CLM on CT scanning.

This study has shown that cRR does NOT mean cPR. While present day chemotherapy drugs are very powerful and can make CLM disappear on CT and USS scanning, what is not shown on scanning the liver does not equate to no disease. USS of the liver at the time of surgery showed that 10.9% of the CLM thought to have cRR by pre-surgery scanning were actually still present and not cRR. The high percentage of recurrent CLM in the liver (74%) of patients with cRR and the detection of live cancer cells in 80% of removed liver tissue showing cRR can only mean one thing. The only sure way of getting rid of the cancer is to completely remove the previously affected area from your body.

As the age old saying goes - Looks can be deceiving!

This weekend Reuters Health News had an article on its web site titled “Increased dietary fish oil may prevent many deaths”. The article was reporting on the findings of a group of researchers from Minnesota who tried to estimate the potential public health benefit of raising adults’ intake of omega-3 fatty acids with fish oil supplements. (Previous studies on regular consumption of omega-3 fatty acids, found in oily fish, have shown that this led to a reduced risk of developing fatal heart rhythm.) Using a computer model of a community of 100,000 Americans, the researchers estimated that the simple act of increasing omega-3 fatty acid levels with fish oil supplements would save 58 lives each year. This equates to a 6.4% total death reduction, mostly from sudden cardiac death in apparently normal people. Even if automated external defibrillator (AED) were available in every household and public place, the study estimated that AED would only lower a community’s annual death rate by less than 1%!

Examples of oily fish are mackerel, sardines, salmon, tuna and swordfish. They are freely available, taste good and will not put a dent in your pocket. The average price for an AED is about US$2,300. The American Red Cross website stated that one of its visions is for all Americans to be within 4 minutes of an AED and that someone be trained to use it in the event of sudden cardiac arrest. Just imagine how much it would cost the government or charitable organizations to buy those AEDs.

Cardiovascular disease (CVD) is a major health problem world wide. It is the No. 1 killer in the United States. Yet by adhering to a healthy diet and lifestyle, we can make a significant impact on CVD without incurring excessive cost on a nation’s health expenditure. In June 2006, the American Heart Association Nutrition Committee published a scientific statement titled “Diet and lifestyle recommendations revision 2006”. Among many of the recommendations is the recommendation to consume fish, especially oily fish, at least twice a week.

Other recommendations such as maintaining a healthy body weight, consuming a diet rich in vegetables and fruits, choosing whole-grain high-fiber foods, choosing and preparing foods with little or no salt and minimizing your intake of beverages and foods with added sugars are not onerous dietary restrictions. They are not difficult to follow and given a bit of effort most, if not all, of the recommendations can be achieved.

We moan and complain when public hospitals cannot give us an appointment to consult with a cardiologist within a week. We curse when the hospital calls to say that your hip operation will only be scheduled 3 months hence. We sometimes forget that we might not have been in that position if we had taken more care with our diet and lifestyle. I can almost hear you say “If only I had had more fish and less bangers and mash when I was younger!”.

As kids, while growing up in the tropics, we would only play outdoors under the strong tropical sun during two periods of the day - before 10.30 in the morning and after 3.30 in the afternoon. We were also frequently reminded of the saying “Only mad dogs and Englishmen go out in the midday sun”. We avoided the period 11 – 3 not because we knew of the danger of sun exposure and skin cancer, it was for the simple reason that it was hot, unpleasant and exhausting to play in the sun then. Almost half a century later, I find my children are having their Saturday extracurricular soccer matches scheduled in the 11 AM – 3 PM period!

Several studies have shown that health behaviours, including unprotected sun exposure, are established early in life and may ‘track’ into adulthood. Most of an individual’s sun exposure occurs during childhood and adolescence. In the northern hemisphere, children spend an estimated 2.5 to 3 hours outdoors each day. They may receive 3 times more annual UV-B rays than adults since in the summer months they are more likely to be out playing in the midday sun.

Epidemiologic studies have shown that sun exposure is the major environmental risk factor for the development of both melanoma and non-melanoma (basal cell and squamous cell carcinoma) skin cancers. The patterns of sun exposure seem to be important in the development of these cancers. Non-melanoma skin cancers have been associated with cumulative sun exposure while melanoma has been associated with short, intense sun exposure or blistering sunburn. Worldwide, it has been estimated that ultraviolet (UV) radiation from the sun is responsible for at least 65% of melanoma cases. In United States non-melanoma skin tumours are the most common skin cancers in the Caucasian population.

Although skin cancers are rare before the age of 20, there is evidence supporting the role of sun exposure during early life and the subsequent risk of skin cancer during adulthood. Using a mathematical model based on epidemiological data, a group of researchers has quantified the potential benefit of using a sunscreen against developing skin cancer. If you were to regularly use a sunscreen, with a sun protective factor of 15, during the first 18 years of life, you would reduce the lifetime incidence of non-melanoma skin cancers by 78%!

A study from Boston and New York looked at the use of sunscreen, sun-burning rates and tanning among 10079 boys and girls, age 12 – 18, from all 50 states (Pediatrics 2002; 109: 1009 – 1014). They found that only 34.4% of teenagers used sunscreen routinely during the previous summer and girls are more likely to use sunscreen than boys. Furthermore, 83% of the teenagers had had at least 1 sunburn during the previous summer and 36% of the teenagers had had 3 or more sunburns. Contrary to expectations, the researchers found few differences in sunscreen use and sun-burning rates in warmer versus cooler states. While the summer months can be hot in USA, I am sure the sun in the tropics can be just as strong and in the tropics the sun is shinning 365 days a year – give or take a few days in a year.

In an effort to influence social norms related to sun protection and tanned skin, the Centers for Disease Control and Prevention launched the ‘Choose Your Cover’ campaign in 1998. The campaign is to increase awareness, knowledge and behaviour related to skin cancer prevention. A recent study by the American Cancer Society looked at the trends in sunburns and sun protection practices in US adolescents during 1998 and 2004 (Pediatrics 2006; 118: 853 – 864). In 1998, 72 % of adolescents had been sunburned during the summer. In 2004, the rate was slightly but not significantly better at 69%. The proportion of youth who reported regular use of sunscreen however did show a significant increase from 31% in 1998 to 39% in 2004.

Using a different approach, a study, involving children from southern Idaho and eastern Tennessee, examined the effectiveness of a parent-based intervention approach to reduce unsafe sun practices in children aged 9 – 12 (Arch Dermatol 2006; 142: 1009 – 1014). Parents in the intervention group received materials that encouraged parents to communicate skin cancer risks, promote sun-safe behaviours and discourage high-risk sun-related behaviours. The study showed that the rate of sunburn, sunburn severity and sunbathing tendencies were most effectively reduced in this group of children. 

Living in a sunny clime does not mean that we cannot enjoy the unlimited sunshine. It just means that we have to be sensible in our enjoyment. While enjoying the sunshine it would be illogical to expose ourselves to unnecessary skin cancer risk. The government has a responsibility to educate and inform the public about the risk of unsafe sun practices. Perhaps a more effective approach is to educate each citizen while he or she is young. Parental attitude and participation play significant roles in educating the young about any subject matter including unsafe sun practices. However, let us not forget that schools have a similar big role to play too. For example, scheduling extracurricular soccer matches at a more sensible part of the day would be a start! After all, the school has a captive audience and exerts great influence on the children in their most formative years.