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The relative and absolute risk of developing breast cancer
The relative and absolute risk of developing breast cancer
Every woman wants to do everything that depends on it to minimize the risk of developing breast cancer. But, unfortunately, we do not yet have sufficient information that can help. Scientists are intensely engaged in clarifying how factors internal and external environment can influence the occurrence of the disease. Reducing the risk of exposure means avoiding the risk factors and increase the impact of protective factors. Is currently under tremendous amount of research devoted to identifying the causes of breast cancer and effective prevention. Therefore, doctors can not yet answer the question of why some women have breast cancer, while others - no.
The factors "internal" environment are factors that are directly related to our health. It's a genetic predisposition, hormonal diseases, including breast cancer and disease, and disease of genital organs, as well as psycho-emotional state.
Among the environmental factors that may influence the risk of developing breast cancer, marked everything that surrounds us: the environment, food, water, air, and stress, including medicines. However, some factors such as genetic predisposition and drugs play a direct role in causing cancer.
And so, all that may increase the possibility of developing breast cancer, called risk factors. Anything that helps to prevent the disease - the protective factors.
Some risk factors can be controlled. For example, obesity - a risk factor, as in adipose tissue is the conversion of androgens into estrogens - a woman can control through diet and exercise. In turn, this helps in the prevention of breast cancer.
Other risk factors can not be prevented, or make it very difficult. For example, you can not change sex. It is known that breast cancer occurs in women more often than breast cancer in men (although the external signs of gender can be changed quickly and hormonal, genetic foot floor will be the same!). In addition, you can not somehow affect the process of natural aging. Although a woman can control many risk factors and protective factors, this does not mean that cancer risk is reduced to zero. In addition, it should be remembered that women with specific risk factors (genetic predisposition), the risk of cancer will never be low or zero.
The risk of breast cancer is every woman. This risk increases with age. At the age of 90 years in women, for example, this risk may already be 14%. It sounds pretty scary, because it means, on average, every seventh woman in 90 years of age suffer from breast cancer. On the other hand you can look at it and the other: the risk of 14% means that 86% of women do not suffer from this disease.
The influence of risk factors and prevention in the overall risk of breast cancer
For every woman it is very important to know that it may increase the risk of breast cancer, and that - to reduce this risk. What do the numbers, for example, if you find that one or the other method can reduce the risk of developing breast cancer by 40%? To do this, you should be familiar with concepts such as relative and absolute risk.
RELATIVE RISK
The relative risk indicates the extent to which may decrease the risk of developing the disease if you take certain actions (eg taking medication) compared to if you have not taken any drugs. Relative risk is expressed as a percentage or ratio of risk. If you do not take anything new, you risk ratio is 1.0 - this means that the risk does not change. If the measures taken reduce the risk score in half, or 0.5, then you have 50% risk of contracting. However, if the risk increases from 1.0 to 1.88, it means an increased risk of cancer by 88%. If the hazard ratio increased to 3.0, it means an increased risk of up to 300%.
The absolute risk
The absolute risk - the risk score is fact. Absolute risk reduction - a percentage number, which changes the actual risk. Let's look at the example of breast cancer risk in women without a history of the disease earlier. Smoking increases the risk of developing breast cancer as well as some other diseases. Let's say your risk of breast cancer is 14%. Smoking increases it by 32% (ie, greater than one-third). This means that the risk of breast cancer from smoking is 32% above 14% if you do not smoke. This is the relative risk.
But how much real influence on the change in the risk of these 32%? In order to find out how the absolute risk, see what happens when your risk is increased by 14% of the third: Multiply your risk by 14% relative increase in risk of 32%. You will receive a 4% (14% x 32% = 4.48% or 4%). 4% - this is how much increased risk. Add the increased risk of 4% to 14% of the initial risk, and you will receive 18%.
This means that the absolute risk of breast cancer is 18% if the woman was not until this breast cancer and she smokes.
Let's look at an example of the risk of breast cancer in women who previously have had the disease. Suppose you are in the past suffered from breast cancer and underwent lumpectomy with clean margins. The risk of cancer in the same breast after lumpectomy zhelezek with clean margins is 30%. However, if after surgery you have had radiation therapy, the risk of cancer recurrence is reduced by two-thirds of 66%. This relative risk reduction.
That really means a reduction in the risk by 66%? In order to find out how the absolute risk, remove the two-thirds of 30% of your risk: Multiply the risk of breast cancer recurrence (30%) of the relative risk reduction with radiotherapy (66%), and you will receive a reduction of 20% (30% x 66% = 19.80% or 20%). In order to determine the remainder of the risk of cancer recurrence after radiotherapy, it is necessary to take away 20% of the initial 30% risk of recurrence. Therefore, the absolute risk of cancer recurrence after radiation therapy is reduced to 10%.
So, how can you, after lumpectomy and radiation therapy "finish off" the remaining 10% of the risk? There are different methods of so-called adjuvant therapy, such as hormonal therapy (tamoxifen or aromatase inhibitors), which lasts five years. Hormone therapy can reduce the risk of cancer recurrence by 50%. Hormonal drugs may reduce the relative risk of cancer recurrence in the same breast by 50%. To find out how changing hormone therapy reduces the absolute risk, subtract from it half the risk of: Multiply your risk on the value of the relative risk reduction while taking tamoxifen (10% x 50% = 5%). Then subtract the 5% of your risk (10% -5% = 5%).
Now, the absolute risk of recurrence of breast cancer is 5%. Thus, radiotherapy and hormone therapy for 5 years reduces the risk of cancer recurrence from 30% to 5%. Knowing how and to what extent changes the risk of cancer and its recurrence when the lifestyle is very important for optimal decision making.
