Silent cancers: here’s what you need to know when there are no obvious symptoms

The recent revelations about the Princess of Wales’s cancer diagnosis highlight a crucial aspect of cancer detection – the disease’s sometimes silent nature.

Silent cancers are those without noticeable symptoms. They pose a unique challenge in early detection and treatment.

Contrary to common perception, cancer does not always announce its presence through overt symptoms or obvious signs. Many people receive a cancer diagnosis incidentally, when it’s found during routine medical examinations or investigations for unrelated health concerns – as seems to be the case for both the princess and King Charles III.

While even silent cancers can sometimes be aggressive and advance rapidly, they can also remain dormant for years or even decades. Some prostate, breast and thyroid cancers, for example, often evolve slowly without obvious symptoms or spreading beyond the original area.

Research suggests that some of these cancers are overtreated. Sometimes patients are best left alone or treated much more gently, perhaps even without medical intervention, using a “watch and wait” strategy. This approach may be taken with prostate cancer in the elderly, for example.

The importance of early diagnosis

Whatever the cancer, it’s always important to get an early diagnosis though – and for silent cancers, this is obviously a challenge.

Some cancer symptoms can be vague and easily mistaken for benign ailments. Fatigue, unexplained weight loss and persistent pain are among the nonspecific symptoms that may signal an underlying malignancy. But such symptoms can be misinterpreted or easily dismissed, which contributes to delayed diagnosis and treatment.

Fortunately, in many countries including the UK, we have screening tests for diseases like breast or colon cancer, to increase early diagnoses.

Early diagnosis is a key factor for successful cancer treatment. Detecting cancer in its silent phase offers a window of opportunity for early intervention and improved outcomes. The discovery of asymptomatic cancers through diagnostic imaging or screening tests underscores the importance of these proactive healthcare measures.

Identifying cancer at an early stage means the disease is confined to its site of origin, smaller and potentially easier to cure. Diagnosing a smaller cancer often means that if an operation is needed, it may be a less invasive surgery. There may also be a lower chance of needing post-operative preventative chemotherapy, to mop up any residual cells.

Colorectal cancer (CRC) is a good example to show the critical importance of screening. Studies show that patients who participate in CRC screening, such as colonoscopies or tests that look for blood in the stool, are more likely to be diagnosed while asymptomatic and have more positive prognoses after treatment. Those diagnosed with CRC after showing symptoms, such as rectal bleeding or changes in bowel habits, tend to have more advanced tumors and poorer outcomes.

Public health initiatives aimed at raising awareness about the importance of both cancer screening and symptom recognition play a pivotal role in reducing diagnostic delays. Empowering people to engage in preventive healthcare measures such as HPV vaccinations and lifestyle changes that decrease risk can facilitate early detection and intervention, potentially altering the trajectory of the disease.

Biomarker discovery

The latest advances in diagnostic technologies, often known as “biomarker discovery”, hold promise for improving early detection rates and refining treatment strategies for silent cancers. From molecular profiling to liquid biopsy techniques (blood tests to diagnose cancer), innovative approaches are reshaping the landscape of cancer diagnosis, offering new avenues for personalised and precision medicine.

For example, I worked with a team using blood tests to identify cancers in more than 1,000 women recalled after screening for mammography. We looked at the DNA that tumour cells release – so-called cell-free DNA – and also metabolomics (rare markers related to metabolism in the blood). From this information, we found healthy patients, benign disease, pre-cancer and breast cancer. Although there’s increasing awareness and use of this approach in Europe, it isn’t standard in the UK.

Asymptomatic cancers represent a formidable challenge for patient care. But, by encouraging patients to adopt preventive lifestyles and engage with screenings and tests, asymptomatic cancers don’t have to be a hidden threat to health.