print

Breast cancer: Introduction

History

Breast cancer was recognised by the Ancient Egyptians as long ago as 1600 BC. The origin of the word cancer is credited to the Greek physician Hippocrates (460-370 B.C.), considered the "Father of Medicine." Hippocrates used the terms carcinos and carcinoma to describe non-ulcer forming and ulcer-forming tumours. In Greek these words refer to a crab, most likely applied to the disease because the finger-like spreading projections from a cancer called to mind the shape of a crab. Hippocrates believed that the body contained 4 humours (body fluids) - blood, phlegm, yellow bile, and black bile. A balance of these fluids resulted in a state of health, while any excesses or deficiencies caused disease. An excess of black bile collecting in various body sites was thought to cause cancer. This theory of cancer was passed on by the Romans and was embraced by the influential doctor Galen's medical teaching, which remained the unchallenged standard through the Middle Ages for over 1300 years.

The 19th century saw the birth of scientific oncology with the discovery and use of the modern microscope. Rudolf Virchow (1821-1902), often called the founder of cellular pathology, provided the scientific basis for the modern pathologic study of cancer. William Stewart Halsted (1852–1922), professor of surgery at Johns Hopkins University, developed the radical mastectomy during the last decade of the 19th century. This method became the basis of breast cancer surgery for almost a century. Halsted did not believe that cancers usually spread through the bloodstream. He believed that adequate local removal of the cancer would be curative - if the cancer later appeared elsewhere, it was a new process.

Stephen Paget (1855-1926), an English surgeon, concluded that cancer cells spread by way of the bloodstream to all organs of the body but were able to grow only in a few organs. This understanding of metastasis became a key element in recognizing the limitations of cancer surgery. It eventually allowed doctors to develop systemic treatments used after surgery to destroy cells that had spread throughout the body and to use less mutilating operations, for example, in treating many types of cancer. Today these systemic treatments may also be used before surgery.

Modern times

Over the past 50 years, breast cancer has become a major health problem affecting as many as one in eight women during their lifetime. The burden of breast cancer is increasing in both developed and developing countries, and in many of the regions of the world, it is now the most frequently occurring malignant disease in women. Figure 1 shows trends in incidence and mortality in the Czech Republic over the past 30 years. At the present time, breast cancer incidence rate in the Czech Republic is approximately 108 newly diagnosed cases per 100.000 women each year. Breast cancer incidence rates vary considerably, with the highest rates in the developed world (USA, Denmark, Switzerland, Belgium) and the lowest rates in Africa and Southwest Asia.

Figure 1: Trends in breast cancer incidence and mortality in the Czech Republic.

Breast cancer mortality rate in the Czech Republic remains relatively stable, i.e. less than half of breast cancer incidence rate. Since 1990s, breast cancer mortality rate of 36-38/100.000 women is comparable to other developed countries in Europe and North America. Breast cancer mortality rates in the US have fallen by 2000-3000 deaths each year; as for Europe, mortality rates have dramatically fallen in countries such as Sweden, Germany, Austria, Greece, Switzerland and United Kingdom. On the other hand, breast cancer mortality rates have increased in other European countries, such as Spain, Portugal, Hungary, Poland and Italy. The reduction in breast cancer mortality rates is likely to have several different causes, including screening (decline by 20-30%) and adjuvant systemic therapy.

The prognosis depends primarily on the stage of disease at the time of diagnosis, and is not significantly affected by local therapy (surgery, radiation therapy). In fact, the prolongation of survival time is only anticipated in case of systemic therapy.

Breast cancer generally affects women in higher age: there is a significant increase in incidence after 40 years of age (see Figure 2). Breast cancer incidence in younger women (up to 40 years of age) was 7,2/100.000 in 1986-1990; 7,3/100.000 in 1991-1995; 6,0/100.000 in 1996-2000; and 7,8/100.000 in 2001-2005. Therefore, it cannot be stated that breast cancer incidence have increased in young women, as it had been presumed. However, the prognosis is much worse in this age group, as the tumours are typically multifocal and are diagnosed too late. Breast cancer is not anticipated in young women, and mammography sensitivity is significantly reduced in a woman’s fertile period of life. Age below 35 years is an independent, prognostically unfavourable factor at the diagnosis of breast carcinoma.

Figure 2: Stratification of breast cancer incidence according to age groups in different time periods (as for the population of the Czech Republic).

In West European countries, breast cancer is the most prevalent cause of death in women below 60 years of age. Women over 60 years are more likely to die of heart disease than breast cancer. This results into a relative decline of breast cancer incidence rate in women over 80 years, as women in this age group generally die of other causes.