A recent review of cancer rates worldwide shows that cancer rates increased in women. This by itself is alarming, but based on that data the rates likely will go up by 60% in the year 2030. The main reason is the smoking discrepancy among women and men. Men as a group have been smoking more than women. But women as a group are more and more embracing smoking. All of the negative health consequences of the last 3 decades for men are just starting to show now for women as well.
The World Health Organization explains it this way: in high-income countries like Australia, Canada, the US and Western Europe women smoke at nearly the same rate as men.
But in low and middle income countries women do not smoke as much as men do. For instance in China 61% of men are smokers, but only 4.2% of women are smoking. In Argentina 34% of men are currently smokers, which compares to 23% of women who smoke in this country.
When this gap will close, likely by the year 2030 women will have a whole host of diverse cancers, heart attacks and strokes caused by the smoking habit.
Some statistics and facts
High-income countries like Australia, Brazil, Canada, Israel and many northern and western European countries have a 5-year survival rate for breast cancer of 85%. In contrast the 5-year survival rates are 60% or less in low- and middle-income countries like South Africa, Mongolia, Algeria and India.
Cancer prevention measures can make a big difference later in life. Examples are hepatitis B vaccination, which will prevent liver cancer; vaccinating boys and girls against HPV, which will prevent cervical cancer in women; also having regular mammograms will detect breast cancer earlier and improve breast cancer survival rates.
Dr. Nestor Esnaola, surgical oncologist at Fox Chase Cancer Center at Temple University Hospital, Philadelphia, PA said that the cancer prevention methods just mentioned might not be available in developing countries. Instead of mammographies repeat breast self-examinations are more important there. Campaigns against smoking can be utilized in order to prevent cancer of the lungs, the throat and neck. And if colonoscopies are not available, stool samples can be tested for blood and hemoglobin to check for colon cancer.
Different cancer rates increased in women in different countries
There are different cancer types that make the top chart for different countries. For instance in 2012 breast cancer was on top of most countries worldwide as the number 2 killer behind heart attacks and strokes. But other cancers ranked fairly high as well as causes of death: colorectal, lung and cervical cancers.
Despite this trend there were other countries like China and North Korea that had a higher incidence of lung cancer rather than breast cancer. The cancer researchers stated that the reason for this is that the smoking rates are higher in these countries. As already pointed out in China more than ½ of the men smoke, but only a small minority of the women smoke. But women in China are exposed to high amounts of secondhand smoke in addition to environmental pollution, which still causes a lot of lung cancer in women who live in this environment.
In many African countries cervical cancer is very common. Women, who are HIV positive, have a 5-times higher rate of cervical cancer. Southern and eastern Africa where there are higher rates of HIV, have higher rates of cervical cancer.
More data about women’s cancer rates
An overview article entitled “Global Cancer Incidence and Mortality Rates and Trends—An Update” points out some interesting statistics. The greatest numbers of cancer cases and deaths occur among women in Eastern Asia. The estimate for 2012 worldwide was for 1.7 million cancer cases and 1 million deaths in women. China dominated its region with 75% of all female cancer cases and deaths in the region. In North America cancer cases and deaths within the US comprise 90% of the region. The cancer cases and deaths in India make up about 65% of the region of South-Central Asia.
The top mortality rates are found in low to medium income countries, namely in Zimbabwe, Malawi, Kenya, Mongolia and Papua New Guinea.
The most frequently diagnosed cancers in women are breast, lung, and colorectal cancers in economically more developed countries. However, the statistics are different for less developed countries where the top three most diagnosed cancers are breast, cervix, and lung. Similarly the leading causes of cancer deaths for women in developed countries are lung, breast, and colorectal cancers. In developing countries the leading causes of cancer deaths for women is cancer of the breast, lung, and cervix.
Cancer frequencies for women in different countries
The American Cancer Society reports that breast cancer is the most common diagnosed cancer among women in 140 countries. Cervical cancer is most common in 39 countries, all of which are low to medium income countries. There are some countries where other cancer types are more common. For instance in China and North Korea lung cancer is more common among women, in Mongolia and Laos liver cancer, and in South Korea it is thyroid cancer.
The most common cause of death from cancer in women is breast cancer in 103 countries, cancer of the cervix in 43 countries and lung cancer in 27 countries. Other most common cancer deaths in women are in the following countries:
- Stomach cancer: in Bhutan, Peru, El Salvador, Guatemala, and Tajikistan
- Liver cancer: in Laos, Mongolia and The Gambia
- Colorectal cancer: in Japan and Slovakia
- Esophagus cancer: in Turkmenistan.
Prevention and early detection
Changing the risk factors could modify 20% of breast cancer mortality worldwide. Avoiding excess body weight, physical inactivity and reducing alcohol consumption could all significantly reduce breast cancer mortality. For instance, women with a body mass index of greater than 35.0 have a 1.6-fold higher risk of breast cancer and a 2.1-fold higher mortality rate from breast cancer than women with a body mass index of less than 25.0.
Regular breast cancer screening with mammography is another tool that will reduce breast cancer mortality as the cancer is diagnosed earlier and treated at an early stage where it can often be cured. The WHO recommends for those countries where mammography programs are established that screening should be done only every two years and only between the ages of 50-69 to avoid X-ray over exposure.
Early detection, like for any cancer is the key for successfully treating breast cancer. When there is an early diagnosis of breast cancer, surgical removal in healthy tissue (lumpectomy) often cures breast cancer. Unfortunately in low to medium income countries the cancer is often found too late, requires more invasive mastectomies and radiotherapy and has a lower survival rate than in developed countries.
Cervical cancer
Cervical cancer accounts for the 4th most frequently diagnosed cancer in the world. In 2012 there were 527,600 cases of cervical cancer worldwide and 265,700 deaths from cervical cancer occurred in the same year. 90% of cervical cancers occur in developing countries with India accounting for 25% of the total cases. The key in detecting cervical cancer is a regular screening program. In developed countries where this has been in place cervical cancer incidence has decreased by 80% in 4 decades. At the other end of the spectrum are countries like Uganda, Zimbabwe, and some countries of Central and Eastern Europe where cervical cancer rates have been climbing.
Human papilloma virus
The reason for the spread is that the human papillomavirus (HPV) is now more common and screening methods for cervical cancer are not in place. HPV 16 and 18 are the most common carcinogenic subtypes of the human papilloma viruses; they are responsible for 70% of cervical cancers worldwide. Vaccinating teenagers before they engage in sex is a powerful tool to interrupt the infectious spread of an important risk factor for cervical cancer.
Cervical swab for HPV-DNA test
Instead of the traditional Pap test from the past the new test that is in use now is an HPV-DNA test, a cervical swab that will detect DNA from HPV directly. It is more sensitive than the traditional Pap test. If the HPV-DNA test is positive, the patient sees a gynecologist who performs a colposcopy test. This is a microscopic exam of the cervix. The gynecologist can use several effective treatment methods like a loop electrosurgical excision procedure, laser ablation therapy, cryotherapy or conization for deeper cervical cancer lesions.
As with any cancer early detection and treatment is paramount with cervical cancer. In developed countries the 5-year survival rate is 60 to 70%. In India the 5-year survival rate is 46%.
Cancer of the lung
In 2012 there were 583,100 cases of lung cancer in women worldwide and 491,200 died from it. Lung cancer is the second leading cause of cancer death in women and the third most common cancer. The statistics of lung cancer reflect the tobacco epidemic. It takes about 20 to 30 years after widespread smoking begins in a country before the deadly statistics set in. The peak of the cancer epidemic and the heart attack rates occurs about 30 to 40 years following the peak of smoking in that population.
Lung cancer rates globally
Lung cancer rates in women have lagged behind men, because women as a group have started smoking later. In places like Hong Kong, the United Kingdom, Australia, and the United States women started smoking earlier, and they are in the process of declining their smoking habit or quitting. The new lung cancer cases and also the lung cancer mortality rates are reflecting this. Sadly, in many countries of Europe and Latin America women started smoking much later and they are still increasing their lung cancer statistics and mortality rates. Lung cancer killed 1.1 million men and 0.5 million women worldwide in 2012. Cancer epidemiologists estimate that in addition there are 21,400 lung cancer deaths annually from second-hand smoke in non-smokers worldwide.
Other causes of lung cancer
Beside smoking there are other risks causing lung cancer. The estimated risk for women to die in millions is: exposure to household air pollution, 1.6; outdoor air pollution, 1.4; second-hand smoke, 0.35; occupational risk factors, 0.10; and residential radon, 0.03.
Cancer Rates Increased In Women
Conclusion
Women are still in the midst of a global increase of cigarette smoking, which starts often with female teenagers. As long as the smoking rate goes up there will be more breast cancer, lung cancer and cervical cancer. The American Cancer Society provided a detailed review of various cancers and how they are still increasing worldwide, because nobody pays attention to preventative measures. A simple step to prevent cancer is to quit smoking. Another step is to engage in regular physical activity. Finally keeping your body mass index under 25.0 is a third step that can be done by adopting a Mediterranean diet.
There are several pockets within the developed countries where cancer rates are coming down, which is encouraging. I illustrated this complex topic by giving an initial overview and then three examples of breast cancer, cervical cancer and lung cancer.
About Ray Schilling
