Lisa Markwell: Only so many lessons to be learnt from Martina

The debate on the benefits and risks of screening has been confusing

Celebrity campaigns are always tricky. Of course teenage girls in their droves go to Topshop – it's because Kate Moss is the in-house designer. And there will be legions of Geordie princess-wannabes that buy L'Oreal shampoo after seeing their heroine Cheryl Cole flicking her (unnaturally extended) tresses on TV. But what about healthcare? Is it helpful when someone in the public eye who has fallen ill embarks on a public information blitz?

The news earlier this week that tennis legend Martina Navratilova is suffering from an early-stage breast cancer has caused major ripples throughout the media. Like Kylie Minogue and Jade Goody before her (what odd hospital-bedfellows), Navratilova becomes a poster girl for a disease, and her television interview on ABC's Good Morning America has already been copiously copied and re-viewed via YouTube. (Unlike Jim Carrey's relationship break-up, a cancer diagnosis is not yet, to my knowledge, a Tweetable matter).

Her decision to speak out about her diagnosis – as with those other celebrities – will undoubtedly cause women around the world to visit their doctors for screening, but it's slightly unnerving that a professional athlete should, after a lifetime of medicals and fitness tests, ignore her screening schedule for four years: the result, she says, of "letting it slide". Navratilova was also shocked, she admitted, by falling prey to cancer despite "staying in good shape".

What hope is there for the rest of us, less in tune with our bodies and with less recourse to the level of healthcare that the elite have? It could cause undue panic, which is just what nobody needs when over-diagnosis is causing such problems.

Recent debate on the benefits and risks of screening for breast cancer has confused many – for while mammograms save two lives for every one who receives unnecessary treatment, stories of gruelling over-treatment leads other women to steer clear of their local breast-care unit. This is particularly true of Ms Navratilova's condition – ductal carcinoma in situ (DCIS) – which is a "pre-cancer" which might never develop into a full-blown tumour.

When I was given the news that the lump in my breast was highly likely to be DCIS, I clung on to that probability like a drowning woman to a branch. The very word cancer is terrifying (although I couldn't call it a "personal 9/11" as Martina did in an unusually crass moment during an otherwise upbeat and informative interview). I spent the first few days and nights persuading myself that I wouldn't need surgery, chemotherapy or radiotherapy because it was "only" DCIS.

Unluckily in my case, it turned out to be cancer in all its glory, so I had all of the above – a process made more difficult by the current medical thinking that empowers the patient to be intimately involved in deciding whether to undergo these gruelling procedures.

As with Navratilova, the temptation to cling to statistics is powerful (she has been told that there is only a one per cent chance of someone with her diagnosis going on to die of breast cancer). And the fact that screening in this country only applies to those between 50 and 70 allows many of us to feel we're outside the danger zone and that we are at risk only from over-diagnosis: but as Martina quipped to her interviewer, "like the cancer knows you aren't 50 and waits..."

Screening raises as many questions as it answers and will continue to do so until it offers results that are cast-iron, rather than open to interpretation. Although the NHS breast screening programme is due to be extended to those between 47 and 73 by 2012, calls to lower the age for cervical cancer screening from 25 to 20 after Jade Goody's death have been rejected because there's too high a risk of over-diagnosis.

Martina Navratilova blames herself for developing cancerous cells because she forgot to have mammograms for four years. Many others conveniently "forget" because it's such an unpleasant, painful and potentially life-ruining test but may reconsider on reading of the plight of one of our most treasured Wimbledon champs (and "I'm a Celebrity" favourite).

The anticipated rush to doctors' surgeries after this and other newsworthy celebrity case-studies could well save lives. But in taking the first step, we must be ready to undertake extensive research to equip ourselves for what lies ahead, and to face difficult decisions about whether, if that murky lump might one day be malignant, to lose our energy, our hair and, potentially, our long-term good health by having harrowing cancer treatment. This is the curse of choice – and it affects everyone from celebrities to you and me.

l.markwell@independent.co.uk