Cancer is a major cause of illness and death in developed countries. The risk of death from cancer has also been increasing in the less developed countries. As improvements in medical care have reduced deaths from infectious diseases and increased life expectancy, cancer has become the leading cause of death in many societies. For example, according to the American Cancer Society, about one in three people in the USA will develop cancer at some point in their life, and about one in four will die from it. Each year about 500,000 individuals die of cancer, a rate of about one death per minute, and more than one million new cases of cancer are diagnosed annually in the US. Currently more than 10 million individuals are receiving medical treatment for cancer in US hospitals and medical centres.

What are the causes of cancer?

Scientific evidence gathered over the last hundred years has dispelled the superstition, once prevalent, that cancer is a contagious disease. But, despite significant advances in the last decade, its underlying mechanisms are still a mystery.

The link between cancer and genetic mutation was shown early in this century: normal cells mutate into malignant ones because of changes in chromosome constitution.

There are four points which support the idea that cancer has a genetic origin:

1. More than 50 forms of cancer are known to be inherited to one degree or another
2. Some tests detecting mutations have shown that most environmental toxic agents which are called carcinogens are also mutagens.
3. Work with cancer-associated viruses has revealed the presence of some mutant genes, known as oncogenes, that promote and maintain tumour growth.
4. The chromosomal abnormalities found in particular forms of cancer, especially leukemia.
5. The environment and behaviour can also play a significant role in the genesis of cancer.

The existence of high rates of specific cancers in particular families has been known since early in the 19th century. Many explanations have been offered for this phenomenon, including multiple gene inheritance, environmental agents or even mere chance.

Hereditary forms of cancer

Recent advances in cancer research have provided some clues about the relationship between mutant genes and the cellular events that lead to tumour formation. Experimental evidence suggests that as few as two mutational events may be sufficient to cause a cell to become cancerous (see Figure I). In those forms of cancer that show a heritable predisposition, the first mutation is present in the germ cells and is transmitted genetically. The second mutations are acquired by somatic cells through spontaneous replication errors or exposure to environmental agents that cause genetic damage, resulting in cancer. On the other hand, not all individuals who inherit the first mutation will develop cancer.

If the second mutational event does not occur, then no tumour will develop. Research has focused particularly on two classes of genes in carcinogenesis: tumour suppressor genes which normally function to suppress cell division, and proto-oncogenes which normally promote cell division. 

Tumour suppressor genes

Tumour suppressors are detected in the form of chromosomal deletions (or other inactivating mutations) that are tumorigenic. The strongest evidence for their nature is provided by certain hereditary cancers. There is also now evidence that changes in these genes may be associated with the progression of a wide range of cancers. About 10 tumour suppressors are known at present. These genes act at certain points to inhibit cell division. These and or their gene products must be absent or inactive for normal cell division to take place. If tumour suppressor genes become deleted or inactivated by mutation, control over cell division is lost, and the cell can proliferate in unchecked fashion. The example of breast cancer illustrates how mutations in tumour suppressor genes are involved in the development of cancer:

The genetic link to breast cancer

In the USA, the ratio of women getting breast cancer is approximately 1 in 8. It is the most common form of cancer in women: 46,000 women die and 182,000 new cases are diagnosed each year. Epidemiological factors may also be involved in breast cancer, but geneticists have focused on the question – Is there a genetic predisposition to breast cancer? Their answer, for the present, is Yes: though involved in only about 5% of all eases, a particular gene has been identified and located on chromosome 17. It is responsible for susceptibility to a form of breast cancer that appears in the third and fourth decades of life. About one in 200 females inherits this gene, and 80% to 90% of these will develop breast cancer. Besides breast cancer, a gene has been found on chromosome 17 in sufferers from astrocitoma (brain tumours), colon, lung and bone cancers. This finding suggests that there is a mutation on this gene (called p53), and as a result the cells start growing abnormally.

The Future

Investigations into the tumour suppressor genes are an example of the recent progress in molecular aspects of cancer research. A better understanding of molecular carcinogenesis and molecular epidemiology will eventually decrease the quantitative and qualitative uncertainties associated with the current state of cancer risk assessment. It may be possible to immunize patients against their tumours by using these findings about genes-cancer relationships. Indeed, determination of the type and number of mutations in p53 and other cancer-related genes in tissues from ‘healthy’ individuals may allow the identification of those at increased cancer risk and their consequent protection by preventive measures.

Although there have been many and most welcome developments in the diagnosis and treatment of diseases, including cancer, there is a definite and reliably cure only for some of the infectious diseases. However, we firmly believe there are definite remedies for all diseases in the universe except death.

References

• HARRIS, ADRIAN L. (1990) ‘Mutant p53-The commonest genetic abnormality in Human Cancer?’ The Journal of Pathology.
• HARRIS, CURTIS C. (1993) ‘p53: At the Cross-roads of Molecular Carcinogenesis and Risk Assessment’, Science, 262.
• CUMMINGS, M. (1994) Human Heredity, West Publishing Company, St Paul. Lewm, B. (1994) Genes 5, Oxford University Press, New York.
• LEWIN, B. (1994) Genes 5, Oxford University Press, New York.

It is estimated that 80 to 90 percent of all cancer cases are related to environmental and lifestyle influences (1). Many cancer research centers estimate that 80 to 90 percent of human cancers are preventable. Beside chemicals and infections (viral and parasitic), extrinsic factors include diet among a variety of other factors wholly or partly determined by personal behaviour. Though genetic factors and age affect cancer onset rates, the conclusion holds that many human cancers are avoidable (2). A great number of these are related to tobacco smoking and chewing, alcohol consumption, homosexuality, promiscuity and excessive exposure to solar radiation as in sunbathing, all practices disapproved in traditionally religious societies.

Dr John Hill, a London physician, reported an increase of lip cancer in pipe smokers as long ago as 1761. Sir Percival Pott reported cancer of the scrotum in chimney sweeps in 1777, which he attributed correctly to lodgement of soot in the rugose scrotal skin. This type of cancer was virtually eliminated by simple personal hygiene (3). Later, many chemicals were proved to be carcinogenic and hence many cancers became avoidable by taking more care when dealing with them. Ionizing radiation is still an important hazard, preventable by taking better care.

Tobacco and Cancers

In many countries cancer is the second most important cause of death. In the USA and many developed countries, it accounts for 20 percent of all deaths (1,2). An estimated 6 million new cases of cancer occur annually worldwide, of which about a million are caused by tobacco smoking and chewing (4). The death toll due to malignant disease in the USA amounts to 400-450,000 annually of which 100,000 are due to lung cancer, 85 to 90 percent of those due to cigarette smoking (1,2). Indeed, tobacco (smoked, chewed or sniffed) is the most important single factor in cancer causation generally, responsible for 30- 40 percent of all cancers (5). No other single agent has been examined in more detail, nor more firmly established as a causal agent, than cigarette smoking (6). Let us look at some of the facts.

The risk of cigarette smokers developing lung cancer increases with the number of cigarettes smoked the duration of smoking, the time of onset and the type of smoking. Approximately one-sixth of those who smoke two packs of cigarettes per day will eventually develop lung cancer. The risk to hose who smoke 40 cigarettes per day are 25 times more that to non-smokers (6-8). Cigarette smoking causes all ol the major types of lung cancer including squamous cell carcinoma, adeno carcinoma, oat cell and large cell carcinoma (6). Cancer of the lung was a rare form of cancer at the beginning of this century, even in developed countries. As smoking increased dramatically after World War I among men, and among women after World War II, the incidence of cancer of the lung showed incessant increase until the seventies, after which it began to decline among men and a decade later among women. Nevertheless, cancer of the lung is still the first killing cancer among men and women in many developed and developing countries (7,9,13). In Hong Kong, the rates for women are now the highest in the world (13). Lung cancer rates in Chinese men (e.g. 50.2 per 100.000 in Shanghai) are higher than in many North American and European populations (13). It is the leading cause of cancer mortality among males in Bulgaria. Cuba, Czechoslovakia, Egypt, Greece, Hong Kong. Hungary, Israel, the Philippines, Poland, Romania, Singapore, Thailand, Uruguay and Zimbabwe. The risk is particularly high among cigarette smokers, and a clear cut dose-response relationship has been confirmed. The risk is greater among those who started smoking at a young age and those who smoke high tar cigarettes (2,14-16).

Laryngeal cancer is the second cancer caused by cigarette smoking, but the total number of cases is smaller than lung cancer and the survival is much better (6). Cigarette smokers are five times more likely to develop cancer of the oral cavity and the oesophagus than non-smokers (&-8). There is synergism between alcohol and cigarette smoking in causing cancer of the larynx oesophagus and oral cavity(6-8.14-16,22).

Cigarette smoking is also an important contributing factor in cancers of the bladder, kidney and pancreas. Association between gastric cancer and smoking has also been noted (23-26). Cigarette smoking has even been implicated in cancers affecting the breasts, kidneys, liver, cervix, uteri and many other organs (27-29). It has also been implicated in childhood cancer as a result of prenatal exposure to parental smoking (30). Passive smoking was implicated in causing many cases of cancer (31-33).

Non-smoked Tobacco

Long term use of chewing tobacco or snuff has been linked to cancer of the oral cavity, cheek, gums and oropharynx (6). Oral cancer is one of the ten most common cancers in the world. In Bangladesh, India, Pakistan and Sri Lanka, it is the most common malignant disease and accounts for a third of all cancers. More than 100,000 new cases occur annually in South and South East Asia (13). The commonest cause for oral cancer is tobacco chewing, usually in the form of betel quid which consists of betel vine leaf (piper betel), areca nut, lime and tobacco (13,34). Tobacco chewing is also widespread in parts of Yemen, Sudan and Southern Province of Saudi Arabia: the so called ‘shamma’ is a tobacco plus lime and ash mix, implicated in many cases of oral cancer in these areas (35,36).

Tobacco was propagated in developed countries by tobacco companies after the decline of cigarette smoking there. The 39th World Health Assembly in 1986 adopted Resolution WHA39 which declared that ‘the use of tobacco in all its forms is incompatible with the attainment of health for alt by the year 2000’ (37). The study group concluded that the use of smokeless tobacco caused cancers in humans, the evidence of causality being strongest for cancers of the oral cavity. It also increased the risk of cancers of the nasal cavity, pharynx, larynx, oesophagus, pancreas and urinary tract. Laboratory studies clearly supported the observations that smokeless tobacco caused a number of precancerous oral lesions (37).

Carcinogens in Tobacco Smoke

Tobacco smoke is an aerosol consisting of about 2000 different substances, 50 of which are already proven to be human carcinogens e.g. Benza pyrines, Benza anthracene, Benzo floaranthene, Benzene and other Benzyl derivatives, cadmium, chrysene, methylchryscne, methyl fiouranthene and nitroso compounds (38,39).

Cigarette smoke also contains significant amounts of radioactive substances e.g. thorium Th228, polonium-210 and radium-Rd226. These compounds lodge in the lungs where they constantly irradiate the nearby cells and hence facilitate malignant change (38). Even the urine of cigarette smokers contains mutagenic substances for bacteria, and substances that cause changes in the chromosomes of human cells in tissue culture.

Sidestream smoke which is inhaled by non-smokers contains fifty fold greater concentration of nitrosamines than mainstream smoke. In one hour of breathing in a smoke filled room, a non-smoker may inhale an amount of nitrosamines equivalent to the amount inhaled after having smoked 15 filter cigarettes (38).

Cessation of Smoking

The risk after cessation of smoking decreases dramatically. Light smokers approximate the risk of nonsmokers after 10 to 15 years of cessation of smoking, while heavy smokers have a residual two to three fold increase after cessation (2,6). The mechanism of lung carcinogenesis and smoking cessation has been extensively studied (40).

Women and Smoking

As women started smoking long after men, there is a time lag in the incidence of lung cancer. The incidence of lung cancer has already fallen for men in most developed countries while it was still increasing for women early in the eighties. In 1984, 32 percent of the women smoked in Britain compared with 36 percent of men. In 1961, the figures had been 60 percent of men, and 40 percent of women. Whereas in 1950 the average woman smoker smoked half as many cigarettes as the average male smoker, in the eighties the corresponding figures were 14 and 16 cigarettes (41).

During the second decade of the anti-smoking campaign in Britain, smoking started to fall among women too, slowly at first, but with accelerating momentum (42). Similar trends are found in all developed countries, In some countries e.g. Australia, smoking among young and middle aged women was rising in the early eighties (5,43A4). The proportion of male smokers was falling in 19 out of 22 developed countries, and for women rising or stable in II countries (42-44). In Austria, Germany, Italy, Japan, U.S.S.R., smoking among women was still rising in the early eighties(42).

We may note that lung cancer has already surpassed breast cancer in the number of fatalities it causes. Non-smoking wives of smoking husbands (passive smokers) and non-smoking women working in smoking environments are also afflicted with lung cancer(6,31-33.37).

Trends in Developed and Developing Countries

Anti-smoking campaigns have been launched in the developed countries in the last three decades with tremendous achievements. In Britain, 60 percent of men were smokers in 1961 (the year before the first report of the Royal College of Physicians about smoking was published). By 1971 this figure had dropped to 47 percent, by 1984 to 36 percent, and by 1992 less than 25 percent of the adult males are smoking. As already noted, a similar trend among women smokers was apparent with a ten-year lag (42-45). The decline in cigarette consumption in other European countries and the USA has been comparable. By the mid-eighties sales had plummeted by an impressive 2$ percent with a 5-10 percent annual decline (42-44).

How have the tobacco companies been selling the 10 billion cigarettes they produce daily? By promoting sales in the poor Third World, already suffering from serious health hazards. Consumption of tobacco in Third World has seen a horrendous increase. The World Health Organization (WHO) has reported that tobacco related diseases are on the rise in developing countries.

During the last three decades: in Senegal the percentage of men who smoke in urban areas has reached an unprecedented 80 percent in Bangladesh 70 percent; in Lagos 72 percent of the Faculty of Medicine male students were smoking (46). Statistics from the Chamber of Commerce of Saudi Arabia show an unbelievable increase in tobacco imports: over 4,5 million kgs in 1972: over 27 million kgs in 1977; nearly 36 million kgs in 1981; 42 million kgs in 1984 – an increase of 900 percent (47-48). It is no surprise to find that lung cancer in Saudi Arabia has increased dramatically – from the twelfth most common cancer in a 1950-61 study (49) to the third most common cancer in a 1979-84 study (50). It is expected to be the leading cancer in the nineties us the effects of smoking are unfolding.

The tobacco companies’ methods are unscrupulous as well as aggressive, with bribery of government officials to permit promotion not unusual. In 1982, the head of the Malaysian parliament retired and went to work as a chairman of Rothman’s, Malaysia’s largest cigarette manufacturer (48-51). Ethiopia imported 200 million expensive British cigarettes in 1984 when a large portion of its population were starving to death (52). In Bangladesh, smoking of five cigarettes daily robs the family of a quarter of its food supply, which results in an estimated 18.000 deaths among children annually (53). Unfortunately, the World Bank and Western Governments are co-operating with the seven giant tobacco companies (three American, three British and one French). The World Bank has given Pakistan 60 million dollars in loans to raise tobacco and the US Food for Peace Programs have spent 2 billion dollars in loans to developing countries for the purchase of U.S. tobacco and to establish joint-venture tobacco projects and factories (48-51). Tobacco needs to be cured with heat, obtained by burning wood. This results in deforesting 7 million acres annually with the obvious detrimental impacts on the local ecology, Heavy use (without protective measures) of carcinogenic pesticides on tobacco plantations has also resulted in many fatalities.

Neither tobacco promotion nor high tar content are restricted in many third world countries. Cigarettes smoked in China. India. Pakistan. Sri Lanka the Philippines etc. contain 21-33mg tar and 2-3mg nicotine: while in tile developed countries of U.S.A., Canada, Western Europe, the maximum legally permitted levels are 15 mg tar and 1 mg nicotine (13,46,48).

China consumes one third of the world’s production of cigarettes, while the other developing countries consume another third (48,54). The Eastern and Western block combined consume the remaining third.

The WHO emphasizes the need for a ban on tobacco promotion which should be comprehensive, fully implemented, well publicized, given major priority by governments and health authorities, and sustained on a long term basis (13).

Islamic Law and Tobacco

Muslim muftis and grand ‘ulama’ proscribed smoking tobacco soon after it was introduced to Turkey around 1000H (1573). Sultan Murad of the Ottoman Caliphate made it a capital offence in 1663. The former Grand Mufti of Saudi Arabia, Sheikh Mohammed bin Ibrahim (55) included in his fatwa the names (If many grand ‘ulama’ and muftis who had proscribed tobacco use since its first appearance in Turkey, Morocco, Egypt, Syria, and Yemen (56). All the religious authorities in Saudi Arabia, including of course the present Grand Mufti, Sheikh Abdul Aziz bin Baz, prohibited tobacco use, its promotion, sale, cultivation or dealing with it in any way other than destroying it.

Recently the 1st International Islamic Conference of ulama’ (On Drugs, Narcotics and Liquors held in Madina, March 22-25, 1982, under the auspices of Crown Prince Abdullah bin Abdul Aziz passed a resolution prohibiting the use of tobacco in any of its forms, its cultivation, manufacture, trading in. selling or promoting it in any way (57). The WHO Eastern Mediterranean office published a book in 1988 under the title Al-Hukm al-Shar’i fi at-Tadkhin (Islamic legal ruling on smoking) which involved the decision of the ten leading ‘ulama’ of Egypt, including Sheikh Al-Azhar, who explicitly considered tobacco use as haram (58).

The grounds for these judgments were:

1. Smoking is detrimental to health. The Qur’an states clearly Don’t kill yourselves (4.29) and Make not your own hands contribute to your destruction (2.195). Islamic teachings generally, as well as hundreds of sayings of the Prophet, upon him be peace, encourage Muslims to preserve good health and abstain from things injurious to health.
2. Tobacco use wastes huge sums of money. Saudi Arabia spends annually more than one billion riyals on tobacco imports (59). Some poor Muslim countries spend more money on smoking and other tobacco use than on health promotion or education. The Qur’an deplores such waste: Squander not your wealth senselessly. Squanderers are indeed the like of Satans (17.26, 27).
3. Smoking is had and impure, khabath. The Qur’an declares that the Prophet, upon him be peace, forbids all that is bad and impure and allows all that is good and clean (7.157). Smoking is bad and impure, as it Causes environmental pollution and is unpleasant, even seriously harmful, to those who do not smoke, injuring others is completely prohibited in Islam and considered one of the worst sins a believer can commit.

There is a great need to inform Muslim communities about the legal opinions on tobacco use and the rationale for them. The Muslim governments should stand firmly against the pressures exerted upon them by the tobacco companies and their powerful Western backers. If Muslim countries and peoples adhere to the traditional religious lifestyles. They will succeed in avoiding the perils and tragic losses of life and wealth caused by tobacco consumption.