astronomy

Million Women Study

Million Women Study is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Million Women Study rather than just read about it. In short: The Million Women Study is a study of women’s health analysing data from more than one million women aged 50 and over, led by Dame Valerie Beral and a team of researchers at the Cancer Epidemiology Unit, University of Oxford. It is a collaborative project between Cancer Research UK and the National Health Service (NHS), with additional funding from the Medical Research Council (UK).

Key takeaways

Million Women Study belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Million Women Study to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Million Women Study from memory before moving on to harder problems.

Reference excerpt

The Million Women Study is a study of women’s health analysing data from more than one million women aged 50 and over, led by Dame Valerie Beral and a team of researchers at the Cancer Epidemiology Unit, University of Oxford. It is a collaborative project between Cancer Research UK and the National Health Service (NHS), with additional funding from the Medical Research Council (UK). One key focus of the study relates to the effects of hormone replacement therapy use on women's health. The study has confirmed the findings in the Women's Health Initiative (WHI) that women currently using HRT are more likely to develop breast cancer than those who are not using HRT. Results from the Million Women Study, together with those of the WHI trial from the USA, have influenced national policy, including recent recommendations on the prescribing and use of hormone replacement therapy from the Royal College of Obstetricians and Gynaecologists and from the Commission on Human Medicines.

Study design The Million Women Study is a multi-centre, population-based prospective cohort study of women aged 50 and over invited to routine breast cancer screening in the UK. Between 1996 and 2001, women were invited to join the Million Women Study when they received their invitation to attend breast screening at one of 66 participating NHS Breast Screening Centres in the UK. At these centres, women received a study questionnaire with their invitation, which they were asked to complete and return at the time of screening. Around 70% of those attending the programme returned questionnaires and agreed to take part in the study, over 1 in 4 women in the UK in the target age group. The Million Women Study is the largest study of its kind in the world.

Aims The Million Women Study was set up with the aim of recruiting 1,000,000 women in the UK into a cohort study, to provide answers to the following questions:

What effects do combined estrogen and progestogen hormone replacement therapy (HRT) preparations have on breast cancer risk? Are breast cancers detected at screening in women who have used HRT or oral contraceptives different in terms of size and invasiveness from the cancers detected in women who have never used these hormones? How does HRT use affect the efficacy of breast cancer screening? How does HRT use affect mortality from breast cancer and other conditions?

Findings

HRT and breast cancer Initial analysis of the results from over 1 million women in the Million Women Study appeared to confirm preliminary findings from other studies at the turn of the century finding that women currently using progestin-estrogen HRT were more likely to develop breast cancer than those who are not using HRT. This initial analysis received extensive press coverage. The initial reading of results showed that this effect is substantially greater for combined (estrogen-progestogen) HRT than for estrogen-only HRT; and that the effects were similar for all specific types and doses of estrogen and progestogen, for oral, transdermal and implanted HRT, and for continuous and sequential patterns of use. Current users of estrogen-progestogen HRT were at 2 fold increased risk of developing breast cancer, and current users of estrogen-only HRT appeared to have a 1.3 fold risk. Use of HRT by women aged 50–64 in the UK in the decade from 1993-2003 was estimated to have caused 20,000 extra breast cancers. Past users were not seen as having increased risk. A reanalysis refuting the initial conclusion that HRT increased the risk of breast cancer, was published in a 2012 paper in the Journal of Family Planning and Reproductive Health Care. The paper's authors, led by Samuel Shapiro of the University of Cape Town, claimed that the study had not in fact establish a causal relationship between HRT and breast cancer, and that the original analysis had been flawed.

HRT and uterine cancer It is well known that post-menopausal women who have not had a hysterectomy are at increased risk of cancer of the endometrium (the lining of the womb) if they take estrogen-only HRT. Follow up of over 700 000 women in the Million Women Study confirmed this and showed that the risk of endometrial cancer is also increased in women who take tibolone; but is not altered, or may even be reduced, in women taking combined estrogen-progestogen HRT. These effects depend also on a woman’s body mass index (BMI, a measure of obesity) such that adverse effects of tibolone and estrogen-only HRT are greatest in thinner women, and the beneficial effects of combined HRT are greatest in fatter women.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Million Women Study

Start with the simplest possible case. Write down what Million Women Study claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Million Women Study before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Million Women Study ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Million Women Study

In research: Million Women Study appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Million Women Study in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Million Women Study is common in secondary-school and first-year university syllabi. It links to neighbouring topics British medical research, Cohort studies, Medical Research Council (United Kingdom), so understanding it makes those chapters shorter.
In everyday life: Look for Million Women Study outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Million Women Study in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Million Women Study means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Million Women Study out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Million Women Study in simple terms?

Why does Million Women Study matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Million Women Study?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Million Women Study.