What about the base rate of getting breast cancer? Am I to understand women still get diagnosed at the same rate but the treatment has gotten better? What happened in the 70s that made it so much more common?
In the 70's Doctors ramped up their prescriptions of Horse Estrogen because they were tricked into thinking it helped. PREMARIN is made from PREgnant MAres' uRINe:
>> In response to the 1962 Kefauver Harris Amendment the FDA had [Premarin's] efficacy reviewed, and in 1972 found it effective for menopausal symptoms and probably effective for osteoporosis [0].
[0] https://en.wikipedia.org/wiki/Premarin#History
Premarin prescriptions fell off a cliff in response to the preliminary findings of the Women's Health Initiative - https://en.wikipedia.org/wiki/Women%27s_Health_Initiative#HT...
Now doctors realize that excess estrogen -> cancer, and are using anti-estrogens for breast cancer:
>> Other improvements have included tamoxifen, an anti-estrogen agent that was approved in the late 1970s; Herceptin, a drug used to treat tumors with a higher-than-normal level of a protein called HER2 and drugs called aromatase inhibitors.
(quote from this article)
Edit: yesterday I commented on a submission about cancer probably being a mitochondrial disease [1]. This is the old/new idea about cancer, that it's not actually caused by genetic mutations - the observed genetic mutations are actually caused by metabolic failure.
[1] https://news.ycombinator.com/item?id=15382104
Edit 2: DES was the first synthetic estrogen. It was used on women until 1971, when they realized it caused cancer [2]. Those women would've developed cancer in the 2-3 decades that followed their exposure to this drug.
[2] https://en.wikipedia.org/wiki/Diethylstilbestrol#Adverse_eff...
That’s not a “side-effect” of it though. Be careful about attributing causation. The effects of testosterone bring about the conditions that lead to these problems.
The same goes for estrogen: women develop breasts as a result of increased levels of estrogen. The increased cellular activity in the breast cells over many decades leads to an increased risk of cancer. It is because the breasts grow that cancer rates greatly increase; they are inseparable to some degree.
This comment is relevant: https://news.ycombinator.com/item?id=15290462
>From 2005 to 2014, overall breast cancer incidence rates increased among Asian/Pacific Islander (1.7% per year), non-Hispanic black (NHB) (0.4% per year), and Hispanic (0.3% per year) women but were stable in non-Hispanic white (NHW) and American Indian/Alaska Native (AI/AN) women. The increasing trends were driven by increases in hormone receptor-positive breast cancer, which increased among all racial/ethnic groups, whereas rates of hormone receptor-negative breast cancers decreased.
See also Figure 5, and the paragraph above it with the subheading of "Incidence" in the "Temporal Trends" section:
>Much of the historic increase in breast cancer incidence rates reflect changes in reproductive patterns, such as delayed childbearing and having fewer children, which are recognized risk factors for breast cancer.[22, 23] Incidence rates of in situ and invasive breast cancer rose rapidly during the 1980s and 1990s (Fig. 5), largely because of increased use of mammography screening in the United States. The widespread uptake of mammography screening inflated the incidence rate, because cancers were being diagnosed 1 to 3 years earlier than they would have been in the absence of screening, and screening also may have led to the detection of indolent cases. Invasive breast cancer rates stabilized between 1987 and 1994, followed by a slower increase during the late 1990s. The continued increase particularly among older women may reflect rising rates of obesity and the use of menopausal hormones, both of which increase the risk of postmenopausal breast cancer, as well as further increases in the prevalence of mammography screening.[24] Around the year 2000, incidence rates began to decline among women ages 50 years and older; and, between 2002 and 2003, breast cancer rates decreased nearly 7%, likely because of the decreased use of menopausal hormones after publication of the Women's Health Initiative randomized trial results linking the use of estrogen plus progesterone menopausal hormone therapy to breast cancer and heart disease.[25-27] The decline occurred primarily in white women and in those who had HR-positive disease.[26, 28] The drop in incidence may also reflect in part the small declines in mammography screening since 2000. The percentage of women aged 40 years and older who reported having a mammogram within the past 2 years increased from 29% in 1987 to 70% in 2000 and dropped to 64% in 2015.[29]
[1] http://onlinelibrary.wiley.com/doi/10.3322/caac.21412/full
Cancers start small and develop into larger problems over time. Consider a hypothetical patient who develops cancer at the age of 70 and dies of it, untreated, at the age of 78.
If the cancer is detected at the age of 75, detection will lower the 5-year survival rate, since the patient dies after three years of "having cancer". If it is detected at 72, detection increases the 5-year survival rate, since the patient now dies after 6 years. Without treatment, early detection has a very strong impact on 5-year survival rates.
This is why Mammograms are every 1 or 2 years. If you could wait 4 years without treatment early detection would be less of an issue.
PS: People generally assume a lump becomes cancer as soon as it starts to form. But the general case is you get a lot of little growths from pre-cancerous cells which are predisposed to cancer. Then one or more of those cells become cancer and then you die fairly quickly after that transition.