Why early cancer treatment matters

Posted: 17/11/2025

Catching cancer early is one of the most important ways to improve a patient’s chances of survival and recovery. When cancer is found before it spreads, doctors have more treatment options and patients are more likely to respond well. According to Cancer Research UK, early detection is key but currently only about 55% of cancers in England are diagnosed early.

A major study by Hanna et al in 2020 looked at how delays in starting cancer treatment affect survival. They focused on seven common types of cancer, bladder, breast, colon, rectum, lung, cervix, head and neck and three types of treatment: surgery, chemotherapy and radiotherapy. 

The findings were clear that even a four-week delay in treatment can increase the risk of death. For example, delaying breast cancer surgery by eight weeks could raise the risk of death by 17% and a 12-week delay could raise it by 26%. During the COVID-19 pandemic, delays in treatment tragically may have caused thousands of extra deaths in countries including the UK, US, Canada and Australia. The study suggests that reducing delays could save as many lives as some new cancer drugs.

Delays can happen for many reasons. Sometimes patients need extra tests or are not medically ready for treatment but often, delays are caused by the healthcare system itself, such as waiting for surgery slots or specialist appointments. The researchers stress that while patients should only start treatment when they are ready, the system should work to avoid unnecessary delays.

This research highlights the urgent need to improve how cancer services are organised. By reducing delays, survival rates could be improved significantly, especially those caused by the system. These findings are meant to guide national policies and planning, not individual treatment decisions, but they show just how critical timely cancer care is for saving lives.

In clinical negligence cases involving delayed cancer diagnosis, proving legal causation is often the most challenging part. It is not enough to show that a doctor or hospital made a mistake (known as breach of duty), the patient must also prove that the delay in diagnosis or commencement of treatment caused a worse outcome. This means showing that, had the diagnosis or treatment happened sooner, the patient would likely have had a better chance of survival or a less severe illness. The legal standard used is the 'balance of probabilities', meaning it must be more likely than not that the delay made a meaningful difference.

Proving causation in a clinical negligence claim is often difficult. Cancer is particularly complex and, even with timely treatment, outcomes can vary. Patients often still need surgery, chemotherapy or radiotherapy regardless of when the diagnosis is made. Because of this, it is hard to prove that a delay directly caused a worse outcome. Independent medical experts are needed to assess whether the delay changed the course of the disease, and they rely on clinical studies and their own experience. For rare cancers or short delays, there may not be enough evidence to support a claim. English law also does not allow claims based purely on a 'loss of chance'. For example, if a delay reduced survival odds from 40% to 25%, that alone is not enough to be awarded compensation.

However, despite the challenges, some claims do succeed. Each case is judged on its own facts and success often depends on strong expert evidence showing a clear link between the delay and the harm suffered. Penningtons Manches Cooper's clinical negligence team deals with oncology cases and has concluded many such claims successfully where the expert evidence has been key. 

Partner Alison Johnson says: "Independent expert evidence is essential in clinical negligence claims involving delayed cancer diagnosis because it provides the court with an objective, professional opinion on whether the care provided fell below acceptable medical standards and whether that failure caused harm. Experts are not there to advocate for either side but to assist the court in understanding complex medical issues and, without credible expert support, a claim is likely to fail.

"In cancer delay cases, expert evidence is particularly important because causation is often complex. It must be shown that the delay in diagnosis made a real difference to the outcome for the claimant such as reducing survival chances or requiring more aggressive treatment. This requires detailed analysis from specialists in oncology, radiology or surgery, depending on the case. The expert must explain how earlier diagnosis would have changed the clinical course, and their opinion must be logically reasoned and based on accepted medical practice."

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