World Cancer Day: What Is Cancer? Symptoms, Diagnosis and Treatment

Created: 01.02.2024 · Last Updated: 19.08.2026 · Category: Medical Oncology · Prepared by the Academic Hospital Web and Editorial Board.

What Is World Cancer Day?

World Cancer Day is observed every year on 4 February to raise awareness about cancer prevention, early diagnosis, access to treatment and the needs of people affected by cancer.

According to World Health Organization data published in 2026, approximately 20.6 million new cancer cases and close to 10 million cancer deaths occurred worldwide in 2024.

Annual new cancer cases are projected to approach 35 million globally by 2050 if current demographic and risk-factor trends continue.

What Is the 2026 World Cancer Day Theme?

The 2026 World Cancer Day theme is “United by Unique.”

The theme highlights person-centred cancer care and recognises that every individual affected by cancer has different needs, circumstances, values and experiences.

What Is Cancer?

Cancer is a broad group of diseases that can affect almost any part of the body.

Normal cell growth is controlled by multiple biological mechanisms. Genetic and epigenetic changes can disrupt these controls, allowing abnormal cells to grow beyond their normal boundaries.

Cancer cells can invade surrounding tissues and, in some cases, spread through the blood or lymphatic system to distant parts of the body.

Cancer is not one single disease. Breast cancer, lung cancer, leukaemia and lymphoma can differ substantially in biology, prognosis and treatment.

What Is Metastasis?

Metastasis occurs when cancer cells spread from the site where the cancer began to another part of the body.

For example, lung cancer that spreads to bone remains metastatic lung cancer rather than becoming a new primary bone cancer.

What Are the Main Types of Cancer?

  • Carcinomas: Cancers arising from epithelial cells.
  • Sarcomas: Cancers arising from bone, muscle, fat or connective tissue.
  • Leukaemias: Cancers of blood-forming tissues.
  • Lymphomas: Cancers arising from cells of the lymphatic system.
  • Multiple myeloma: Cancer arising from plasma cells.
  • Melanoma: Cancer arising from melanocytes.
  • Brain and central nervous system tumours include several different tumour types.

Common cancers include lung, breast, colorectal, prostate, stomach, liver, pancreatic, bladder, kidney, thyroid, uterine, cervical and ovarian cancers.

What Are the Risk Factors for Cancer?

Cancer usually does not result from one single cause. Age, inherited susceptibility, environmental exposures and lifestyle-related factors can interact.

Important modifiable risk factors include:

  • Tobacco use and exposure to tobacco smoke
  • Alcohol consumption
  • Overweight and obesity
  • Physical inactivity
  • Unhealthy dietary patterns
  • Excessive ultraviolet exposure
  • Certain occupational and environmental carcinogens
  • Air pollution
  • Cancer-associated infections including HPV and hepatitis B and C

Can Cancer Be Prevented?

Not every cancer can be prevented, but a substantial proportion of cancers can be avoided through established evidence-based prevention strategies.

Risk can be reduced by avoiding tobacco, maintaining a healthy body weight, remaining physically active, following a balanced diet, limiting alcohol, protecting the skin from excessive ultraviolet radiation and receiving HPV and hepatitis B vaccination when recommended.

What Are the Symptoms of Cancer?

Symptoms vary according to the type and location of the cancer.

Possible symptoms include:

  • Unexplained weight loss
  • Persistent unexplained fatigue
  • A new or enlarging lump
  • Unexplained bleeding
  • Persistent cough or hoarseness
  • Persistent changes in bowel or bladder habits
  • A sore that does not heal
  • Changes in a mole or skin lesion
  • Persistent unexplained pain
  • Difficulty swallowing
Having one of these symptoms does not mean that a person has cancer. However, unexplained symptoms that persist for several weeks or worsen should be medically assessed.

Why Is Early Diagnosis Important?

For many cancers, diagnosis at an earlier stage can provide more treatment options and may improve outcomes.

There is, however, no universal percentage that describes the chance of successful treatment for all cancers detected early.

Outcomes depend on the cancer type, biological subtype, stage, molecular characteristics, the patient's overall health and the treatments available.

What Is Cancer Screening?

Cancer screening means testing people who do not have symptoms to look for certain cancers or precancerous changes.

Cancer screening is not the same as a general health check-up.

There is no population screening test proven to be beneficial for every type of cancer. Screening should be selected according to cancer type, age, sex, family history and other risk factors.

Evidence-based screening methods can include, in appropriate groups:

  • Mammography for breast cancer
  • HPV and/or cervical cytology testing for cervical cancer
  • Stool-based tests or colonoscopy for colorectal cancer
  • Low-dose CT for lung cancer in selected high-risk individuals
A screening test does not diagnose cancer. An abnormal screening result may require additional imaging, endoscopy or biopsy to determine whether cancer is present.

How Is Cancer Diagnosed?

Evaluation usually begins with medical history and physical examination.

Depending on the suspected cancer, testing may include laboratory tests, ultrasound, CT, MRI, PET/CT, mammography or endoscopic examinations.

For many solid tumours, definitive diagnosis relies on biopsy and pathological examination.

Molecular and genomic tests can also help guide treatment decisions in selected cancers.

What Does Cancer Stage Mean?

Staging describes how far a cancer has spread in the body.

For many solid tumours, staging considers the size and local extent of the primary tumour, regional lymph-node involvement and whether distant metastases are present.

Stage is important for treatment planning, although molecular and biological characteristics of the tumour are increasingly important as well.

What Are the Main Cancer Treatment Options?

Cancer treatment is individualised according to the type, stage and molecular features of the cancer and the patient's overall health.

  • Surgery
  • Radiotherapy
  • Chemotherapy
  • Targeted therapy
  • Immunotherapy
  • Hormone therapy
  • Stem-cell or bone-marrow transplantation for selected haematological cancers
  • Radionuclide therapies for selected cancers
  • Supportive and palliative care

One or several of these approaches may be used as part of an individual's treatment plan.

Cancer Data in Türkiye

Cancer burden in Türkiye can be assessed using national cancer-registry data and estimates published by the International Agency for Research on Cancer through the Global Cancer Observatory.

The current GLOBOCAN platform released in 2026 provides updated 2024 estimates of cancer incidence and mortality.

Cancer patterns differ between men and women and between individual cancer types.

There is no single overall “cancer treatment success rate.” A percentage such as 60%, 70% or 90% cannot accurately describe all cancers. Survival and treatment outcomes must be evaluated separately according to cancer type, stage, tumour biology and patient characteristics.

Cancer Treatment Is Individualised

Cancer type, stage, pathological and molecular characteristics and the patient's overall health are considered together when planning treatment.

Frequently Asked Questions

What is cancer?
Cancer is a broad group of diseases in which abnormal cells can grow uncontrollably, extend beyond their normal boundaries, invade nearby tissues and in some cases spread to distant parts of the body.
What are common symptoms of cancer?
Possible symptoms include unexplained weight loss, persistent fatigue, a lump, unexplained bleeding, persistent cough, changes in bowel or bladder habits and a sore that does not heal. These symptoms are not specific to cancer.
Does early diagnosis guarantee that cancer can be cured?
No. Early diagnosis can improve treatment options and outcomes for many cancers, but the chance of successful treatment depends on cancer type, biological characteristics, stage and individual patient factors.
Can a general check-up detect every cancer early?
No. A general check-up is not a validated screening programme for all cancers. Evidence-based cancer screening is selected according to cancer type, age, sex, family history and other risk factors.
Can cancer be prevented?
Not every cancer is preventable. However, avoiding tobacco, maintaining a healthy weight, remaining physically active, limiting alcohol, protecting against excessive UV exposure and receiving HPV and hepatitis B vaccination when recommended can reduce cancer risk.
Does every cancer patient need chemotherapy?
No. Treatment may include surgery, radiotherapy, chemotherapy, hormone therapy, targeted therapy, immunotherapy and other approaches. Treatment is selected according to the type and characteristics of the cancer.
What does metastasis mean?
Metastasis is the spread of cancer cells from the organ or tissue where the cancer began to another part of the body through the blood or lymphatic system.
Academic Hospital note: Cancer screening, diagnosis and treatment should be planned according to individual risk factors and the characteristics of the disease. General online information does not replace an individual oncology assessment. You can book an appointment.

References

  1. Academic Hospital. World Cancer Day
  2. World Health Organization. Cancer – Fact Sheet, 2026
  3. World Health Organization. Global Status Report on Cancer 2026
  4. International Agency for Research on Cancer. Global Cancer Observatory – Cancer Today
  5. National Cancer Institute. Cancer Screening
  6. National Cancer Institute. Symptoms of Cancer