DataBreast cancer (all types)

Direct links plus the targets, companies, and technologies of this cancer's products.

• What breast cancer is. The breast is a branching tree of fifteen to twenty duct systems, each ending in lobules, the clusters of sacs that make milk. Almost all breast cancer begins where the smallest duct meets its lobule, the terminal duct lobular unit, and the names of the two commonest kinds are therefore misleading in a useful way: neither invasive carcinoma of no special type, still widely called invasive ductal carcinoma, nor invasive lobular carcinoma starts where its name suggests. What really separates them is E-cadherin, the protein that glues cells to their neighbours: lobular cancers have lost it, so they spread in single files instead of forming a lump, which makes them harder to feel, harder to see on a mammogram and harder to measure. While the cancer is still inside the duct or lobule it cannot spread and is called carcinoma in situ; once it has crossed the basement membrane it is invasive, and can reach the lymph nodes in the armpit and, from there or through the blood, the bones, liver, lungs and brain.
• Why the receptors decide everything. Breast cancer was the first cancer shown to be driven by a hormone that could be taken away: Beatson removed the ovaries of women with advanced breast cancer in 1896, and it worked in some of them. Most breast cancers are fed by oestrogen through the oestrogen receptor in the nucleus, and blocking that receptor or removing the hormone works; a minority instead make far too much of a growth-signal protein called HER2 on their surface, and antibodies and antibody-drug conjugates aimed at HER2 work; and a minority have neither, so neither treatment applies and chemotherapy, immunotherapy and, for people with an inherited BRCA fault, PARP inhibitors are used. That is why the first question after diagnosis is not how big or how far, but which of these the cancer is, and why NICE asks for all three receptor results to be requested at once on the first biopsy rather than one after another (NG101 1.3.1).
• Is grade the same as stage? No, and confusing them is the commonest misunderstanding on a breast report. Grade is how abnormal the cells look under the microscope, from 1 to 3, and it is a property of the cancer's behaviour. Stage is how much cancer there is and how far it has gone, from 0 to IV, and it is a property of the situation. A small grade 3 cancer and a large grade 1 cancer are different problems, and the report gives you both because neither can be worked out from the other. The UK dataset makes the same point about its own staging system: the UICC classification, it says, does not incorporate histological grade or receptor status, which is why the Nottingham Prognostic Index and PREDICT exist to put them back together.
• Why the numbers on my report are given to the nearest whole grade and my friend's cancer had an Oncotype score. Grade, size and node status are measured in the hospital laboratory and are on every report. A genomic recurrence score, such as Oncotype DX, MammaPrint, Prosigna or EndoPredict, is an extra test sent away in some hormone receptor-positive, HER2-negative, node-negative cancers to decide whether chemotherapy is worth adding, and it is not done in all cases and not in other subtypes. It is not a better version of the grade; it answers a narrower question, and NICE has separate diagnostics guidance on which of these tests may be used.
• How the outlook is described, and how it is not. Population figures for breast cancer are averages over everyone diagnosed in a period, and for this cancer they are unusually favourable: 76.6 percent of UK women survive ten years or more, and five-year relative survival in the United States is 91.9 percent across all breast cancer. They are also unusually stratified: 95.8 percent five-year survival in hormone receptor-positive HER2-negative disease against 78.7 percent in triple-negative disease, and within triple-negative disease 92.8 percent when it is localised against 14.9 percent when it is distant (SEER 21, 2016 to 2022). No one of those numbers is a prediction about a person, and the number that moves them most is not the subtype but the stage at which the cancer was found.
• Living with breast cancer, the decisions that are shared: This is orientation from public patient pages, guidelines and the trials themselves, not advice for your case: your own team's instructions and 24-hour number come first, and no figure on this page is a prediction about you. The seven decision rows above, the question sets for the surgeon, breast care nurse, oncology, radiotherapy planning, fertility and lymphoedema appointments and for partners and carers, the first 60 days checklist and the red cards were written from NICE NG101, NG257, NG234 and CG151 and from the NHS, Macmillan, Cancer Research UK, Breast Cancer Now and Maggie's, with every trial figure taken from the trial's own publication rather than from a summary of it.
• On what is here and what is not. Breast cancer is three diseases wearing one name, and the pages for hormone receptor-positive, HER2-positive and triple-negative disease carry the drug decisions that follow the receptor result. This page carries only what is true whichever result comes back: the operation, the armpit, the arm, fertility and the menopause, the body you are left with, hair, and follow-up. Where a subtype page says it better, this page points there rather than saying it again.
• On the survival figures. They come from two randomised trials that followed people for twenty years, the Milan trial of 701 women with cancers under 2 cm and NSABP B-06 with 1,851 women, both started in the 1970s, and from the EBCTCG meta-analysis of 10,801 women in 17 radiotherapy trials. They describe those cohorts, treated with the surgery and drugs of their time. They are quoted because the alternative, the phrase similar outcomes, tells a reader nothing about what is actually being traded. No sentence on this page is a forecast for one person.
• On the word women. NICE writes several of these recommendations about women specifically, including the reconstruction and menopause sections, and the wording is kept as NICE wrote it rather than quietly broadened. Everywhere else this page says people, because about 420 of the roughly 59,000 breast cancers diagnosed in the UK each year are in men, and the male breast cancer page exists for them. The lymphoedema section of NG101 says the same thing in its own rationale: the committee recognised that while breast cancer predominantly affects women, men can also be affected, and extrapolated the evidence to make recommendations that address the needs of all breast cancer patients.
• On lymphoedema, which is the reason this layer exists in the form it does. It is lifelong, it affects more than one in five people after axillary clearance, it is badly covered on almost every page a newly diagnosed person will read, and nearly everything that reduces it is decided in the first month: which armpit operation, whether radiotherapy replaces clearance, whether anyone measured the arm before surgery, and whether anyone explained the early signs. NICE rewrote its recommendations on it in 2025 and they are quoted at length above for that reason.

The same record for scripts and assistants; checked 2026-09-25. Data CC BY-NC 4.0, attribute “Data from OnCo (onco.cc)”.