How to revise for CO2A

If you're several months out from CO2A, the temptation is to open a textbook at page one and start reading. That approach sits awkwardly against the exam's actual format: two 120-question single-best-answer papers spanning eleven tumour groups plus imaging (see the complete guide to CO2A for the exam structure in full). Reading builds recognition; the exam tests something closer to judgement — weighing five plausible options against each other under time pressure. What follows is a practical way to revise that matches how the exam actually works, built around four habits: covering the curriculum deliberately rather than by comfort, using question-bank practice to expose what you don't know, spacing that practice out instead of cramming it, and rehearsing full papers under timed conditions before the day itself.

Work the blueprint, not your comfort zone

CO2A's two papers are built around fixed tumour-site groupings, not a random sample of the curriculum. That structure is useful precisely because it tells you where the gaps are likely to be before you find them in the exam hall. Most registrars already think in one subspecialty — the site they work in day to day — and have an unglamorous corner of the curriculum they quietly avoid because it doesn't come up on their ward round. Haematological malignancy, the general medicine and surgery content folded into the syllabus, and the paediatric/thyroid/sarcoma/acute-oncology miscellaneous cluster are the usual culprits, precisely because none of them is any one trainee's daily bread.

The fix is mechanical rather than motivational: build a coverage tracker — a simple spreadsheet with every tumour group as a row — and mark off each one as you complete a first pass, a question-bank pass and a review pass. The tracker itself doesn't matter; what matters is that a written record stops "I'll get to gynae eventually" from quietly becoming "I never got to gynae." Revise the groups you find least interesting earlier in your timeline, not later, when time pressure will make you skip them again.

Question-bank practice: the wrong answers are the point

Working through single-best-answer questions is not really about the answer you pick. Five plausible-looking options exist because each wrong option represents a way trainees actually go wrong — a dose that's right for the wrong indication, a staging cut-off that's one T-stage out, a trial result attributed to the wrong regimen. Reading the explanation for the option you got right and skipping the other four wastes most of the educational value of the question.

The habit worth building is to read every per-option explanation — including the ones for options you correctly rejected — and ask why each was wrong specifically, rather than accepting "not A" as good enough. Over enough questions, this builds the same skill the exam tests: discriminating between answers that are each individually plausible and only wrong on a specific detail. It is also the most efficient way to find your own knowledge gaps, because a question you get right for the wrong reason won't show up as an error anywhere else — the per-option explanation is often the only place that mistake gets caught before exam day. This is the specific gap cited question banks such as FRCR Vault are built around: the answer alone tells you what's right; per-option feedback tells you why the alternatives aren't, which is the more transferable skill.

Spaced repetition: let forgetting do some of the scheduling

A single pass through a topic, however careful, decays fast if it isn't revisited. The practical fix is to schedule review deliberately rather than trust that reading something once will stick: come back to a topic a few days after first covering it, again after a couple of weeks, and again a month or so later, instead of reading it once and assuming it's banked. This matches two well-established findings from cognitive psychology on how memory actually works: distributing study across separated sessions produces better long-term retention than massing the same amount of study into one sitting (Cepeda et al., 2006), and the act of retrieving information — being tested on it — strengthens memory more than re-reading it does (Roediger & Karpicke, 2006). In practice for CO2A, that means treating question-bank practice itself as the spacing mechanism: cycling back through a tumour group's questions weeks after your first pass does more for retention than adding another first pass through material you haven't touched yet.

You don't need dedicated spaced-repetition software to get most of the benefit — a simple rule (revisit each tumour group's questions at roughly one week, one month, and again in the final six weeks before the exam) covers the bulk of it without extra tooling.

Timed mocks: rehearsing the exam, not just the content

Content knowledge and exam performance are not the same skill. CO2A's format rewards pacing as much as knowledge — three hours to work through 120 questions per paper (see the complete guide for the full structure) — and pacing is not something you read your way into. Sit at least a handful of full-length, timed mock papers in the run-up to the exam, ideally split across session-1 and session-2 content so you rehearse both groupings, and treat the time pressure as part of what you're practising rather than an inconvenience to work around.

A mock paper is also the best diagnostic you'll get of where your revision has actually landed versus where you think it's landed. Mark it honestly, log which tumour groups produced the wrong answers, and feed that straight back into your coverage tracker — a mock's real value is the list of gaps it hands you afterwards, not the score itself.

Fitting revision around a clinical rota

Registrar rotas do not leave generous blocks of free time, and the honest answer is that most CO2A revision happens in short, imperfect windows rather than long weekend sessions. Question-bank practice suits this well because a single question with its explanation takes a few minutes, which makes it realistic to fit in on a post-take morning, between clinics, or while waiting for theatre to start, in a way a chapter of reading is not. Protecting one longer session a week — even ninety minutes — for the things short bursts don't cover well, such as a full mock paper or working through a whole tumour group's coverage tracker, stops the short daily sessions from becoming purely reactive.

On-call and post-take weeks will inevitably produce lighter revision weeks. Building a small amount of slack into your overall timeline for this, rather than assuming every week will be a full-intensity week, stops the last month turning into a crisis response to weeks that were always going to be lighter.

The last month

By four weeks out, new topics should be mostly finished; the last month is for closing gaps and consolidating, not opening new ground. Prioritise the coverage tracker's weakest rows, sit the timed mocks you haven't yet sat, and go back through your question-bank history for the questions you got wrong the first time — a wrong answer from weeks ago is exactly the kind of thing spaced review should be catching now, before it resurfaces on the day. If a whole tumour group is still thin at this point, it is more efficient to consolidate it properly than to add a superficial pass across everything else.

The last week

The final week is for maintenance, not acquisition. Keep doing short bursts of question-bank practice to keep recall warm, but do not try to cram genuinely unfamiliar material this late — content learned in the last few days is the least likely of anything you've studied to be retrievable under exam pressure. Re-read your own notes on your weakest tumour groups rather than reaching for fresh sources, confirm your exam-day logistics (venue, start time, ID, permitted materials), and protect sleep over the final 48 hours rather than trading it for extra revision hours. A tired brain weighing five plausible options against each other for three hours performs worse than a rested one that has covered slightly less.

References

• Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249–255. PMID: 16507066.
• Cepeda, N. J., Pashler, H., Vul, E., Wixted, J. T., & Rohrer, D. (2006). Distributed practice in verbal recall tasks: A review and quantitative synthesis. Psychological Bulletin, 132(3), 354–380. PMID: 16719566.