What Is The Incidence Of Breast Cancer

Lifetime Risk Of Breast Cancer Worldwide

Women who live in developed countries tend to have a higher lifetime risk of breast cancer than women who live in developing countries .

Although we dont know all the reasons for these differences, lifestyle and reproductive factors likely play a large role .

Low screening rates and incomplete reporting can make rates of breast cancer in developing countries look lower than they truly are and may also explain some of these differences.

How Common Is Breast Cancer

Breast cancer is the most common cancer in women in the United States, except for skin cancers. It is about 30% of all new female cancers each year.

The American Cancer Society’s estimates for breast cancer in the United States for 2021 are:

• About 281,550 new cases of invasive breast cancer will be diagnosed in women.
• About 49,290 new cases of ductal carcinoma in situ will be diagnosed.
• About 43,600 women will die from breast cancer.

Breast cancer mainly occurs in middle-aged and older women. The median age at the time of breast cancer diagnosis is 62. This means half of the women who developed breast cancer are 62 years of age or younger when they are diagnosed. A very small number of women diagnosed with breast cancer are younger than 45.

What Are The Signs And Symptoms Of Breast Cancer

There are many different signs and symptoms of breast cancer, so regularly checking your breasts for anything different or new is important.

The earlier breast cancer is diagnosed, the better the chance of successful treatment. Getting to know what your breasts look and feel like normally means its easier to spot any unusual changes and check them with your doctor. Common breast cancer signs and symptoms include:

• A lump or swelling in the breast, upper chest or armpit. You might feel the lump, but not see it.
• Changes in the size or shape of the breast
• A change in skin texture i.e. puckering or dimpling of the skin
• A change in the colour of the breast – the breast may look red or inflamed
• Rash, crusting or changes to the nipple
• Any unusual discharge from either nipple

Over a third of women in the UK do not check their breasts regularly for potential signs of breast cancer.

According to a YouGov survey commissioned by Breast Cancer Now, a third of those who do check their breasts for possible signs and symptoms dont feel confident that they would notice a change.

Asked what stops or prevents them from checking their breasts more regularly, over half forgetting to check, over a third not being in the habit of checking, a fifth not feeling confident in checking their breasts, not knowing how to check , not knowing what to look for and being worried about finding a new or unusual change .

Some factors are outside our control, including:

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Antibiotic Use And Breast Cancer Risk

Several large database studies including Group Health Cooperative and the Saskatchewan prescription database show an increased risk with long-term use that rises to a twofold increase with over a total of 1,000 days of use. Other comparable pharmacy record systems have not shown as strong a relation. No clear drug class effect has been observed. This evidence, though still evolving, nevertheless points to the possibility that modification in the gut microbiome through extended use of antibiotics may significantly modify risk of breast cancer.

Summary Of Postmenopausal Hormone Use And Breast Cancer Risk

Although some aspects of the relationship between postmenopausal hormones and breast cancer risk remain unresolved, several areas of clear agreement have emerged. Combination estrogen plus progestin therapy is carcinogenic in women and causes breast cancer. The adverse effect of combination therapy is greater than that observed for estrogen alone. Whether some forms of progestin are safer remains under study.

Overall, the findings indicate an increased risk in two important subgroups of users: users of long duration and current users. In general, users of long duration are more likely to be current users, so, in many studies, these two groups overlap substantially. From a biological perspective, these are the groups one would most expect to demonstrate a relationship with breast cancer risk, as exogenous estrogens appear to act as a promoter at a late stage.

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Additional Insights On Metastatic Breast Cancer Recurrence

CS Breast Cancer Facts and Figures 2013-14Breast Cancer Survival and Stage at Diagnosis Relative survival rates are an estimate of the number of patients who will survive for a given time after a cancer diagnosis. It differs from observed survival in that it accounts for deaths from other causes by comparing among cancer patient to survival among people of the same age and race who have not been diagnosed with cancer. Based on the most recent data, relative survival rates for women diagnosed with breast cancer are:

• 89% at 5 years after diagnosis
• 83% after 10 years
• 78% after 15 years

Of course, women keep dying of MBC longer than 15 years after their initial diagnoses, notes Musa Mayer, patient advocate and Member, Steering Committee, Metastatic Breast Cancer Alliance. According to SEER statistics: 18-year relative survival for patients diagnosed from 1990-1994 is 71% which takes us really close to the 30% figure. However, its important to bear in mind that none of these patients would have been offered Herceptin, not even in the metastatic setting. With adjuvant Herceptin cutting recurrence rates in half, this is a big difference. Fewer hormonal options existed as well.

Breast Cancer Risk Before Menopause

A pooled analysis of data from 7 studies found higher blood estrogen levels is linked to an increased risk of breast cancer in premenopausal women .

Study selection criteria: Prospective nested case-control studies with at least 100 breast cancer cases, pooled analyses and meta-analyses.

Table note: Relative risks above 1 indicate increased risk. Relative risks below 1 indicate decreased risk.

This table shows breast cancer risk related to total estradiol levels.

* Relative risk for estrogen receptor-positive and progesterone receptor-positive breast cancers was 2.8 . Relative risk for estrogen receptor-negative and progesterone receptor-negative breast cancers was 1.1 .

Relative risk for ER-positive cancers only. Relative risk for ER-negative breast cancers was 1.65 .

Results are for estradiol blood levels measured in the follicular phase of the menstrual cycle. Results for estradiol levels measured in the luteal phase of the menstrual cycle were not statistically significant.

|| Relative risk for women with higher levels of free estradiol compared to women with lower levels of free estradiol was 1.75 .

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Breast Cancer Mortality Rates Over Time

Breast cancer mortality rates in the U.S. increased slowly from 1975 through the 1980s .

From 1989-2018 , the breast cancer mortality rate decreased by 41 percent due to improved breast cancer treatment and early detection . Since 1989, about 403,200 breast cancer deaths in U.S. women have been avoided .

The breast cancer mortality rate in women decreased by about one percent per year from 2014-2018 . Different breast cancer mortality rate trends may have been seen in some groups of women.

Mortality Rates And Number Of Breast Cancer Deaths

Sometimes its useful to have an estimate of the number of people expected to die from breast cancer in a year. This number helps show the burden of breast cancer in a group of people.

Numbers, however, can be hard to compare to each other. To compare mortality rate in different populations, we need to look at mortality rates rather than the number of breast cancer deaths.

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In Situ Breast Carcinoma Incidence

• There are around 8,300 new breast carcinoma in situ cases in the UK every year, that’s 23 every day .
• In females in the UK, breast carcinoma in situ accounted for around 8,300 new cancer cases every year .
• In males in the UK, breast carcinoma in situ accounted for around 30 new cancer cases every year in 2016-2018.
• Incidence rates for breast carcinoma in situ in the UK are highest in people aged 65 to 69 .
• Each year around a tenth of all new breast carcinoma in situ cases in the UK are diagnosed in people aged 75 and over .
• Since the early 1990s, breast carcinoma in situ incidence rates have tripled in the UK. Rates in females have around tripled , and rates in males have around doubled .
• Over the last decade, breast carcinoma in situ incidence rates have increased by almost a third in the UK. Rates in females have increased by around a third , and rates in males have remained stable .
• Most in situ breast carcinomas are intraductal.
• In situ breast carcinoma is more common in White females than in Asian or Black females.
• Breast carcinoma in situ incidence rates in England in females are 28% lower in the most deprived quintile compared with the least, and in males are similar in the most deprived quintile compared with the least .
• Around 910 cases of breast carcinoma in situ each year in England in females are linked with lower deprivation.
• An estimated 63,800 women who had previously been diagnosed with in situ breast carcinoma were alive in the UK at the end of 2010.

Distribution Of Cases And Deaths By World Region And Cancer Types

There were an estimated 19.3 million new cases and 10 million cancer deaths worldwide in 2020 . Figure presents the distribution of all-cancer incidence and mortality according to world region for both sexes combined and separately for men and women. For both sexes combined, one-half of all cases and 58.3% of cancer deaths are estimated to occur in Asia in 2020 , where 59.5% of the global population resides . Europe accounts for 22.8% of the total cancer cases and 19.6% of the cancer deaths, although it represents 9.7% of the global population, followed by the Americas’ 20.9% of incidence and 14.2% of mortality worldwide. In contrast to other regions, the share of cancer deaths in Asia and Africa are higher than the share of incidence because of the different distribution of cancer types and higher case fatality rates in these regions.

• a New cases exclude basal cell carcinoma, whereas deaths include all types of nonmelanoma skin cancer.

Figure 4

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What Is Secondary Breast Cancer

Secondary breast cancer is when breast cancer spreads from the breast to other parts of the body, becoming incurable. Breast cancer most commonly spreads to the bones, brain, lungs or liver.

While it cannot be cured, there are treatments that can help control certain forms of the disease for some time and relieve symptoms to help people live well for as long as possible.

There are an estimated 35,000 people living with secondary breast cancer in the UK. In around 5% of women, breast cancer has already spread by the time it is diagnosed.

Receptor Status And Histologic Subtypes Of Breast Cancer

Consistent evidence from larger epidemiologic studies shows combination estrogen plus progestin and unopposed estrogen therapy are associated with increased risk of estrogen receptorpositive breast cancer. While the WHI did not observe any significant difference in the distribution of invasive cancer by receptor status, the trial had limited power to detect an association with fewer than 500 cases of breast cancer. While it has been suggested that risk is limited to lobular subtypes of breast cancer, most evidence does not support this claim, and, given the higher proportion of receptor-positive tumors in lobular rather than ductal cancers, a stronger RR observed for lobular cancer would be expected for this subset of breast cancers.

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Early Detection And Mammographic Screening

Mammographic screening for women aged 5069 years is effective in reducing breast cancer mortality, and reductions in mortality have been observed where screening has been introduced . Evidence that at least part of this decline can be attributed to screening comes from the expected increase in incidence of early stage and in situ breast cancers, followed by a decline in advanced cancer and subsequent mortality in the UK, northern Europe and Australia . It has been estimated that about one-third of the overall 21% reduction in breast cancer mortality in the UK by 1998 was due directly to screening , although the time lag before any benefits from screening can be expected , together with the reduction in mortality resulting from notable advances in treatment , makes quantification of the contribution of each problematic. One of the indirect beneficial effects of screening might have been a shift towards earlier diagnosis of breast cancer, as a result of the publicity surrounding the disease and its prevention.

Invasive Breast Cancer Incidence

The American Cancer Societys estimates for breast cancer in the United States for 2016 are:

• About 246,660 new cases of invasive breast cancer will be diagnosed in women.
• About 61,000 new cases of carcinoma in situ will be diagnosed .
• About 40,450 women will die from breast cancer.

*initial diagnosis only-does not include metastatic recurrences

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Trends In Incidence And Mortality Around The World

Since the 1950s, breast cancer incidence has been increasing in many of the lower-risk countries, as well as in high-risk Western countries. Some of the recent increases in incidence in high-risk populations may be due in part to greater use of mammography, as in the United States. This appears to be the case in Sweden and in England and Wales. However, in Norway, a substantial increase in breast cancer incidence occurred between 1983 and 1993 despite low use of mammographic screening.

Breast cancer incidence rates have nearly doubled in recent decades in traditionally low-risk countries such as Japan and Singapore and in the urban areas of China. Dramatic changes in lifestyle in such regions brought about by growing economies, increasing affluence, and increases in the proportion of women in the industrial workforce have affected the population distribution of established breast cancer risk factors, including age at menarche and fertility and nutritional status, including height and weight. These changes have resulted in a convergence toward the risk-factor profile of Western countries.

Breast Cancer Is An Issue That Affects Us All

• Breast cancer is the most common type of cancer in women in Canada and the second leading cause of cancer deaths in Canadian women.
• An estimated 26,300 women will be diagnosed with breast cancer every year in Canada, and 5,000 women will die from it.
• In Quebec, an estimated 6,000 women are diagnosed with breast cancer yearly, and 1,350 women die from it.
• Women aged 50 to 69 have the highest rate of breast cancer. Among the women between the ages of 20 and 49 that ave been diagnosed with cancer, 18% of them have breast cancer. It is actually the leading cause of cancer deaths in this age group.

In Canada, it is also estimated that 210 men will be diagnosed with breast cancer each year and 60 will die from it. Learn more about male breast cancer here.

These statistics indicate that if these trends continue:

• 1 in 8 women will develop breast cancer in her lifetime.
• 1 in 31 women will die of breast cancer.

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Type Dosage And Mode Of Delivery Of Estrogen

Growing epidemiologic data now address the effects of dose and type of estrogen on breast cancer risk. Data from the pooled analysis show no significant differences in the magnitude of risk were observed according to either the type of estrogen used or the estrogen dose . Although the effect of estrogen use on breast cancer risk could be reasonably hypothesized to vary by mode of estrogen delivery , no important differences were observed in the largest study to date. The Million Women Study included over 40,000 users of transdermal estrogen and observed no significant difference in RR of breast cancer compared to that among the 60,000 users of oral therapy .

Differences By Race And Ethnicity

Some variations in breast cancer can be seen between racial and ethnic groups. For example,

• The median age of diagnosis is slightly younger for Black women compared to White women 63 years old).
• Black women have the highest death rate from breast cancer. This is thought to be partially because about 1 in 5 Black women with breast cancer have triple-negative breast cancer – more than any other racial/ethnic group.
• Black women have a higher chance of developing breast cancer before the age of 40 than White women.
• At every age, Black women are more likely to die from breast cancer than any other race or ethnic group.
• White and Asian/Pacific Islander women are more likely to be diagnosed with localized breast cancer than Black, Hispanic, and American Indian/Alaska Native women.
• Asian/Pacific Islanders have the lowest death rate from breast cancer.
• American Indian/Alaska Natives have the lowest rates of developing breast cancer.

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