Adolescent and Young Adult Cancers: Recognition and Early Diagnosis in Primary Care

Medical Education & Update for General Practitioners (GPs) and Family Physicians

Part 1 of Bridging the Gap: A Primary Care Guide to Adolescent and Young Adult Oncology

Clin Assoc Prof Eileen Poon, Senior Consultant, Division of Medical Oncology,
National Cancer Centre Singapore

Cancers in adolescents and young adults often present with non-specific symptoms, making early diagnosis challenging. This article outlines key epidemiology, red flags and referral considerations to support timely recognition in primary care.

CASE STUDY

RG* was 18 years old when she experienced unexplained weight loss, breathlessness and unrelenting fevers that left her waking up drenched in sweat. Concerned, she sought medical attention from multiple general practitioners (GPs). Each time, she was reassured that she likely had the common cold - understandable given her age and the non-specific nature of her symptoms.

Over the next two months, she gradually grew weaker while her symptoms worsened. It was only when she was finally brought to hospital that she was diagnosed with stage 2 Hodgkin’s lymphoma.

RG started on six months of intensive chemotherapy and radiotherapy. Besides the physical battle, she faced profound psychological challenges—anger at the unfairness, social isolation from peers, a forced gap year spent in hospitals, and constant anxiety with every follow-up appointment.

When treatment ended successfully, RG experienced unexpected emotions—not just relief, but a sense of abandonment. Returning to school proved difficult; she felt fundamentally changed and unable to relate to friends and family as before. While everyone expected her to “bounce back”, her academic performance suffered, and she became increasingly anxious and depressed, hypervigilant about every symptom being a sign of relapse.

The turning point came during a routine GP visit for “stomach cramps”. Instead of just treating her symptoms, the GP recognised that she was struggling with depression and anxiety. He referred her for counselling and she was prescribed antidepressants, which was life-changing for RG.

Although RG is now married and doing well, she has fertility concerns and regrets not pursuing fertility preservation before cancer treatment.

This case illustrates three critical lessons that highlight the important role of GPs:

• The challenge of early cancer detection in young patients with non-specific symptoms 
• The ongoing psychosocial impact on patients even after successful treatment 
• The vital role of GPs throughout the entire cancer journey.

*Name has been abbreviated to protect the privacy of the patient

WHAT IS ADOLESCENT AND YOUNG ADULT ONCOLOGY

Adolescent and Young Adult Oncology (AYAO) refers to specialised cancer care for patients aged 16 to 45 years at diagnosis. This population accounts for 5% to 7% of all cancer cases, compared with just 1% for paediatric cancers. The National Cancer Centre Singapore (NCCS) sees about 500 new AYA cancer cases annually, with over 6,000 AYA patients treated between 2018 and 2021.

WHY SPECIALISED SUPPORT FOR AYA MATTERS

Cancer is the leading cause of non-accidental death in AYAs, highlighting the critical need for timely diagnosis and appropriate care in this age group. AYAs also face unique challenges that differ from paediatric and older adult cancer patients, both during treatment and survivorship.

Cancer strikes AYAs during an important stage of their lives when they are gaining independence, studying, starting careers and forming relationships. A diagnosis not only interrupts these milestones, but it can completely change their life plans. Many cancers in AYAs are aggressive and require prompt treatment. While younger patients usually respond well to treatment, delays in diagnosis can significantly affect treatment outcomes.

Unlike younger children who have parents caring for them or older adults with established support networks and financial stability, AYAs often face cancer with fears about mortality, an uncertain future and peers who cannot understand what they are going through. With decades of life ahead of them, every decision from treatment, fertility preservation to supportive care will impact the next 40 to 60 years of their lives.

Traditionally, cancer awareness campaigns and resources have been largely focused on older patients and children, leaving AYAs without age-appropriate support. As such, AYAs with cancer often fall through the cracks and are not able to get the support they need as they are too old for paediatric services and face different needs from older adult patients. This can result in poorer outcomes compared to other age groups with similar cancer diagnoses.

COMMON CANCERS AMONG AYAs IN SINGAPORE

Understanding which cancers affect AYAs in Singapore helps doctors recognise the warning signs more effectively. The most common AYA cancers vary depending on the age group.

For ages 15 to 24, blood cancers like leukaemia and lymphoma are the most common. Other cancers include thyroid cancer, germ cell tumours, brain tumours and sarcomas.

For ages 25 to 39, breast cancer is increasingly common, especially in Asian populations. Lymphomas, including both Hodgkin and Non- Hodgkin types, sarcomas, melanoma and cervical cancer, linked to HPV infection, are also commonly diagnosed.

In Singapore, blood cancers make up a large portion of cancers in AYAs. Between 2015-2019, NCCS found that 83.1% of AYAs had lymphomas, mainly Diffuse Large B Cell Lymphoma and Peripheral T-cell Lymphoma, and 16.9% had leukaemia.

Some cancers that we usually see in older people, such as colorectal cancer, are now increasingly diagnosed in younger patients. This means we cannot assume someone is too young to have cancer based on their age alone.

THE CHALLENGE OF TIMELY DIAGNOSIS IN AYAS

Why Diagnosis Gets Delayed

The case of RG - who saw multiple GPs over two months before receiving a cancer diagnosis - is unfortunately common. Delays in diagnosing cancer among AYAs can be due to several reasons.

Low index of suspicion in younger patients

One factor is low clinical suspicion. Neither patients nor doctors typically expect cancer in the young and otherwise healthy individuals. Non-specific symptoms such as fatigue, weight loss and pain are usually thought to be due to other common conditions such as anxiety, stress, infections, irritable bowel syndrome, post-viral syndromes or lifestyle factors rather than cancer. Since these symptoms develop over time, they may not seem worrying at first.

Socioeconomic factors

AYAs tend to prioritise work, studies or personal commitments over health. They may not have a regular general practitioner (GP), which makes follow-up and continuity of care challenging. Others may face financial difficulties or lack adequate health insurance coverage.

Lack of routine screening and fragmented care

Lastly, cancer screening programmes are typically recommended for older individuals, so AYAs are not routinely screened for cancer. As AYAs also often switch healthcare providers at different stages of life, their care can become fragmented, leading to delays in diagnosis and treatment.

Why Early Diagnosis is Critical

Early detection of cancer is critical as it can increase the chance of successful treatment and survival, reduce the aggressiveness of treatment required, and improve the overall quality of life for those diagnosed. In comparison, a late-stage diagnosis usually results in aggressive, prolonged treatment with more side effects and significantly disrupts education and career plans.

An early diagnosis also provides crucial time for AYAs to undergo fertility preservation counselling and procedures before urgent treatment begins, avoiding rushed decisions. A cancer diagnosis is devastating at any stage, but detecting it early gives patients the psychological comfort of knowing they have “caught it early” and have a better chance of recovery.

GP’s Critical Role: Early Recognition and Referral

Maintaining Appropriate Clinical Suspicion

Maintaining a calibrated suspicion for cancer is crucial to minimise the risk of missed diagnosis. When symptoms persist despite appropriate treatment for presumed common conditions, it is important to reassess what could be causing them. Keep cancer in mind even while pursuing more likely diagnoses.

WHEN TO INVESTIGATE FURTHER

Constitutional Symptoms

• Unexplained weight loss > 7 kg in 1-2 months (or > 5% body weight) 
• Extreme fatigue affecting daily activities, not improving with rest 
• Persistent fever without obvious infection 
• Night sweats drenching clothes or bedding

Haematological Malignancy Indicators

• Easy bruising or bleeding without trauma 
• Persistent fatigue beyond normal tiredness 
• Swollen lymph nodes that don’t resolve (especially > 2cm or > 2 weeks) 
• Any supraclavicular lymphadenopathy (always investigate urgently)

Solid Tumour Presentations

• Persistent lumps or swellings in breast, neck, armpit, or groin 
• New moles or changes in existing moles (ABCDE criteria) 
• Persistent cough > 3 weeks (especially in non-smokers) 
• Difficulty swallowing or changes in voice 
• Persistent abdominal pain or changes in bowel habits 
• Unusual vaginal bleeding or discharge 
• Any testicular mass, hardness, or painless swelling

Pain and Other Symptoms

• Persistent bone pain not improving with standard treatment 
• Headaches with concerning features (worse in morning, associated with vomiting, neurological changes) 
• Changes in appetite or eating patterns 
• Any persistent symptom without a clear cause

WHEN TO REFER

Immediate Referral (within 2 weeks)

• Confirmed or highly suspicious malignancy on examination or imaging 
• Suspected haematological malignancy (unexplained bruising, bleeding, concerning blood counts) 
• Suspected brain tumour (progressive neurological symptoms, papilloedema) 
• Testicular mass 
• Suspicious breast mass, regardless of age 
• Supraclavicular lymphadenopathy

Semi-Urgent Referral (within 2 to 4 weeks)

• Multiple worrying symptoms that persist despite treatment 
• Complex or rare tumour types that may benefit from specialised AYA expertise 
• Family history that suggests hereditary cancer syndromes 
• AYAs with significant psychosocial risk factors or complex family situations

CONCLUSION

It is important for GPs to be aware of common cancers in AYAs, the challenges in diagnosing this age group and the unique difficulties they face. However, diagnosis is only the beginning. Beyond referral, GPs continue to play an important role in supporting AYAs through treatment, recovery and long-term followup. In the next issue of Defining Med, we explore how GPs continue to play a key role by working together with the NCCS AYAO Clinical Service in supporting AYAs through treatment and survivorship.

Clinical Assistant Professor Eileen Poon’s passion is in Adolescent and Young Adult Oncology (AYAO), and she is working towards training specifically in this area. This is a field in its infancy, especially in Asia, combining both the science and art of Oncology and Medicine.

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