Cancer is a broad group of diseases in which abnormal cells grow uncontrollably and may invade nearby tissues or spread to other parts of the body. There are more than 100 recognized types of cancer, and each type can behave differently.

A cancer diagnosis can raise many questions. What type of cancer is it? What symptoms should be monitored? How is cancer diagnosed? What does the stage mean? Which treatment options are available?

The answers depend on several factors, including the type and subtype of cancer, its stage, specific characteristics of the tumor, the person’s overall health, previous treatments and the goals of treatment.

This cancer treatment guide explains the major cancer types, common symptoms, diagnostic process, cancer staging and the treatment options doctors may consider.

What Is Cancer?

Cancer develops when changes in cells cause them to grow and divide in an uncontrolled way.

Normally, cells grow, divide and eventually die according to the body’s biological processes. Cancer cells can behave differently. They may continue multiplying when they should not, form tumors in some cases, invade surrounding tissues and potentially spread to distant parts of the body.

Not every abnormal growth is cancer. Benign tumors, for example, are not cancerous and generally do not invade distant tissues.

Cancer can begin almost anywhere in the body, which is why cancer is not considered one single disease.

Major Types of Cancer

Cancer is commonly classified according to where it starts or the type of cell involved.

Some cancers form solid tumors, while others primarily affect blood-forming tissues or the immune system.

Common cancer categories include:

Breast cancer
Lung cancer
Prostate cancer
Colorectal cancer
Skin cancer
Liver cancer
Kidney cancer
Pancreatic cancer
Bladder cancer
Thyroid cancer
Uterine and endometrial cancers
Ovarian cancer
Brain and nervous-system cancers
Leukemia
Lymphoma
Multiple myeloma

The National Cancer Institute maintains an extensive list of cancer types, including common cancers and rarer forms.

Solid Tumor Cancers

Solid tumors develop in organs or tissues.

Examples include:

Breast cancer
Lung cancer
Prostate cancer
Colorectal cancer
Pancreatic cancer
Liver cancer

Treatment can vary considerably even among solid tumors because cancers can have different subtypes and biological characteristics.

Blood Cancers

Blood cancers include conditions such as leukemia, lymphoma and multiple myeloma.

These cancers affect blood-forming tissues, blood cells or the immune system and may require different diagnostic and treatment approaches from solid tumors.

Common Signs and Symptoms of Cancer

Cancer symptoms can vary significantly depending on where the cancer develops, how large it is and whether it affects nearby organs or tissues.

Some cancers may cause noticeable symptoms, while others can be detected through screening or testing before symptoms appear.

Possible signs and symptoms include:

Unexplained weight loss
Persistent or unusual fatigue
A new lump or swelling
Changes in the skin
A sore that does not heal
Persistent cough or hoarseness
Unusual bleeding or bruising
Changes in bowel habits
Changes in urination
Persistent or unexplained pain
Difficulty swallowing
Persistent fever or night sweats
Changes in a mole or other skin mark

These symptoms do not automatically mean cancer. Many can be caused by infections, inflammation, injuries, benign conditions or other medical problems.

A symptom that persists, worsens or represents a significant unexplained change should be discussed with a qualified healthcare professional.

Cancer Symptoms by Body System

Understanding symptoms in context can help people recognize changes that may deserve medical attention.

Breast Changes

Possible warning signs can include a new lump, changes in breast appearance, nipple changes or unusual discharge.

Many breast changes are not cancerous, but new or persistent changes should be evaluated.

Respiratory Symptoms

Persistent cough, unexplained shortness of breath or continuing hoarseness can have many causes.

When these symptoms persist or worsen, a healthcare professional can determine whether additional testing is appropriate.

Digestive Symptoms

Changes in bowel habits, persistent abdominal discomfort, difficulty swallowing or unexplained blood in stool can have numerous causes.

Persistent changes should be evaluated rather than assumed to be cancer.

Urinary Changes

Changes in urination or blood in the urine can result from several conditions.

A medical evaluation can help determine the underlying cause.

Skin Changes

A new or changing mole, an unusual skin growth or a sore that does not heal can require professional assessment.

Screening and examination can be particularly important when a skin change is new or continuing.

When Should You See a Doctor?

There is no single symptom that proves a person has cancer.

However, persistent or unexplained changes should not simply be ignored.

The National Cancer Institute recommends speaking with a doctor when symptoms continue for several weeks, while also noting that many cancer-like symptoms are caused by conditions other than cancer.

A healthcare professional may consider:

Medical history
Family history
Physical examination
Screening history
Laboratory testing
Imaging
Additional diagnostic procedures

Early evaluation can help identify the cause of symptoms and determine whether further investigation is needed.

How Is Cancer Diagnosed?

There is no single test that can diagnose every type of cancer.

The diagnostic process depends on the suspected cancer and the patient’s symptoms or screening results.

Doctors may use several types of evaluation.

Medical History and Physical Examination

The first step may include questions about:

Symptoms
How long symptoms have been present
Previous illnesses
Medications
Family history
Lifestyle factors
Previous screening results

A physical examination may then help identify areas that require additional investigation.

Blood and Laboratory Tests

Laboratory testing can provide useful information about a person’s health and may help doctors investigate certain cancers.

Blood tests alone generally cannot establish a cancer diagnosis for most cancers.

Imaging Tests

Imaging can help doctors look inside the body and identify abnormalities.

Depending on the suspected cancer, imaging may include:

X-rays
Ultrasound
CT scans
MRI
PET scans
Other specialized imaging

The appropriate test depends on the clinical situation.

Biopsy

A biopsy involves removing a sample of tissue or cells for examination.

For many cancers, a biopsy is an important part of confirming the diagnosis. The National Cancer Institute notes that a biopsy is often the only way to determine with certainty whether cancer is present in a particular situation.

The exact biopsy technique depends on where the suspected cancer is located.

Understanding Cancer Staging

After cancer is diagnosed, doctors may perform additional tests to determine its stage.

Cancer staging describes how much cancer is present and where it is located.

Doctors may evaluate:

Tumor size
Nearby lymph nodes
Whether cancer has spread
Location of cancer
Other characteristics of the disease

Staging is important because it helps the medical team understand the extent of the cancer and plan treatment.

The meaning of a particular stage can vary depending on the type of cancer, so stage numbers should always be interpreted in the context of that specific cancer.

What Is Biomarker Testing?

Some cancers contain specific biological characteristics that can influence treatment decisions.

Biomarker testing examines certain genes, proteins or other characteristics associated with a tumor.

The results may help doctors identify treatments that are more appropriate for a particular cancer.

The National Cancer Institute notes that biomarker testing can help doctors choose cancer treatments in appropriate situations.

Biomarker testing is not necessary or useful in exactly the same way for every cancer, so the treating team determines whether it is appropriate.

Main Cancer Treatment Options

Cancer treatment depends on the type of cancer, stage, tumor characteristics, overall health and treatment goals.

Many patients receive more than one form of treatment.

Common cancer treatment options include:

Surgery
Chemotherapy
Radiation therapy
Immunotherapy
Targeted therapy
Hormone therapy
Stem cell or bone marrow transplantation
Other specialized treatments
Clinical trials

Let’s look at these options more closely.

Cancer Surgery

Surgery involves removing cancer from the body when this is medically appropriate.

It may be used to:

Remove a localized tumor
Reduce tumor size
Determine the extent of disease
Relieve symptoms
Treat certain complications

Whether surgery is appropriate depends on the cancer’s location, size, stage and relationship to surrounding structures.

Some patients may receive surgery as their primary treatment, while others may receive additional treatment before or after surgery.

Chemotherapy

Chemotherapy uses medicines that can kill cancer cells or stop their growth.

Because chemotherapy medicines can circulate throughout the body, chemotherapy is considered a systemic treatment.

It may be used:

Before surgery
After surgery
Alongside radiation
For advanced cancer
To control cancer growth
To relieve cancer-related symptoms

The specific medicines and schedule depend on the cancer type and treatment plan.

Radiation Therapy

Radiation therapy uses high doses of radiation to damage cancer cells and shrink or control tumors.

It is often considered a local treatment because radiation is directed toward a particular area.

Radiation may be used:

Before surgery
After surgery
Alongside other treatments
To control a tumor
To relieve symptoms

The type and schedule of radiation therapy depend on the cancer and treatment objective.

Immunotherapy

Immunotherapy helps the body’s immune system recognize and fight cancer.

It can be used for certain cancers and may work differently from traditional chemotherapy.

Immunotherapy is not appropriate for every cancer or every patient. Doctors may consider tumor characteristics, biomarkers, cancer stage and previous treatments when determining whether it is suitable.

Targeted Therapy

Targeted therapy focuses on specific changes within cancer cells that help them grow, divide or spread.

Unlike treatments that affect many rapidly dividing cells, targeted medicines are designed around particular molecular targets.

Before using some targeted treatments, doctors may perform testing to determine whether the cancer contains the relevant target.

Hormone Therapy

Some cancers depend on hormones to grow.

Hormone therapy can slow or stop the growth of cancers that use particular hormones.

It is commonly associated with certain breast and prostate cancers, although hormone-related treatment approaches vary by cancer type.

Stem Cell Transplant

Stem cell or bone marrow transplantation may be used in selected blood cancers and other conditions.

The procedure can restore blood-forming stem cells after intensive treatment such as high-dose chemotherapy or radiation.

It is a specialized treatment that requires careful evaluation because it can involve significant risks and intensive monitoring.

Clinical Trials

Clinical trials study new or improved approaches to cancer prevention, diagnosis or treatment.

Depending on the cancer type and eligibility requirements, a clinical trial may provide access to treatments that are still being studied.

Patients considering a clinical trial should discuss the potential benefits, risks, alternatives and eligibility requirements with their cancer-care team.

The National Cancer Institute maintains resources for finding cancer clinical trials.

How Doctors Choose a Cancer Treatment

Cancer treatment is not selected using the diagnosis alone.

A cancer-care team may consider:

Cancer Type

Different cancers respond differently to treatment.

Cancer Subtype

Two cancers that begin in the same organ can have different biological characteristics and treatment options.

Cancer Stage

The extent of cancer can influence whether treatment focuses on removing the tumor, preventing recurrence, controlling disease or managing symptoms.

Biomarkers

Specific genetic or molecular characteristics can sometimes help identify appropriate targeted or immune-based treatments.

Overall Health

Other medical conditions can affect which treatments are appropriate.

Previous Treatment

If cancer has returned or has already been treated, the medical team considers previous therapies when planning the next approach.

Treatment Goals

Treatment may focus on eliminating cancer, reducing the risk of recurrence, controlling disease, extending life or improving quality of life.

The American Cancer Society notes that treatment recommendations can differ between patients even when they have similar cancers because of differences in cancer characteristics and individual health factors.

Can Cancer Treatment Include More Than One Therapy?

Yes.

Many cancer treatment plans combine different approaches.

For example, depending on the cancer, a treatment plan might involve:

Surgery → chemotherapy → radiation

Drug therapy → surgery → additional treatment

The exact sequence varies significantly.

The National Cancer Institute states that many people receive a combination of treatments, such as surgery together with chemotherapy and radiation therapy.

Managing Cancer Treatment Side Effects

Cancer treatment can cause side effects, although the type and severity depend on the treatment and the individual.

Possible treatment-related effects can include:

Fatigue
Nausea
Appetite changes
Hair loss
Skin changes
Mouth problems
Changes in blood counts
Digestive problems
Pain
Neuropathy

Not every patient experiences the same side effects.

Patients should tell their healthcare team about new or worsening symptoms because many treatment-related problems can be managed or treated.

Supportive and palliative care can also be used to manage symptoms and improve quality of life during cancer treatment. The American Cancer Society notes that palliative care can be provided at different stages of serious illness, including during cancer treatment.

The Importance of Follow-Up Care

Cancer care does not necessarily end when the primary treatment is completed.

Follow-up may involve:

Physical examinations
Blood tests
Imaging
Monitoring for recurrence
Managing long-term treatment effects
Medication review
Emotional and practical support

The frequency and type of follow-up depend on the cancer and treatment history.

Patients should follow the schedule recommended by their healthcare team and report new or persistent symptoms.

How Patients Can Prepare for Cancer Treatment

A cancer diagnosis can feel overwhelming, but organizing information can make the treatment process easier to understand.

Keep Medical Records Organized

Maintain copies of:

Pathology reports
Imaging reports
Laboratory results
Medication lists
Treatment plans
Previous medical records

Ask About the Diagnosis

Patients can ask their medical team:

What type of cancer is it?
What subtype is it?
What stage is it?
Has it spread?
Are biomarker tests appropriate?
What treatment options are available?
What are the goals of treatment?

Understand the Treatment Plan

Ask about:

Expected treatment duration
Treatment schedule
Possible side effects
Monitoring requirements
Follow-up appointments
Other available options

Discuss Costs and Practical Needs

Cancer treatment can involve medical and non-medical expenses.

Patients may need to consider:

Treatment costs
Medicines
Diagnostic testing
Transportation
Accommodation
Time away from work
Caregiver support
Follow-up care

Discussing financial concerns early can help identify available support and assistance.

Final Thoughts

Cancer is not one single disease. It includes many different cancers with different causes, biological characteristics, symptoms, diagnostic approaches and treatment options.

A proper diagnosis usually requires more than one piece of information. Doctors may combine medical history, physical examination, laboratory testing, imaging and, when appropriate, biopsy and other specialized tests. Cancer staging then helps determine how extensively the disease has developed and supports treatment planning.

Treatment may involve surgery, chemotherapy, radiation therapy, immunotherapy, targeted therapy, hormone therapy, stem cell transplantation or combinations of these approaches. The most appropriate treatment depends on the specific cancer, its stage and characteristics, the patient’s overall health and the goals of care.

Anyone experiencing persistent or unexplained symptoms should seek evaluation from a qualified healthcare professional rather than trying to diagnose cancer based on symptoms alone.

Disclaimer: This article is provided for general educational and informational purposes only. It is not medical advice and should not be used to diagnose, prevent or treat cancer or any other medical condition. Cancer symptoms, diagnostic procedures, treatment options, risks and outcomes vary significantly between individuals and cancer types. Always consult a qualified healthcare professional or oncology team for an individualized evaluation, diagnosis and treatment plan. Do not delay or change medical treatment based solely on information presented in this article.