What Is Chemotherapy and How Does It Treat Cancer?

Chemotherapy, often referred to simply as “chemo,” is a type of cancer treatment that uses powerful drugs to stop or slow down the growth of cancer cells, which tend to divide and spread rapidly.

These chemotherapy drugs circulate throughout the body via the bloodstream, making them effective at targeting cancer cells that have spread to other areas of the body (metastasized) beyond the original tumor site. 

Based on the type of cancer, chemotherapy can be used alone or in combination with other treatments like immunotherapy, radiation therapy, or surgery. 

It’s one of the most well-established and widely used forms of cancer treatment, having played a central role in oncology for over 70 years. From shrinking tumors before surgery to eliminating microscopic cancer cells after surgery, or controlling advanced disease, chemotherapy can be administered at any stage and type of cancer. 

This guide breaks down the core elements, whether you have been recently diagnosed with cancer, want to support someone, or are trying to make sense of the situation. It provides an in-depth outline of the chemotherapy process, including how chemotherapy works, its side effects, and other pertinent information.

Understanding Chemotherapy

Chemotherapy Definition and Meaning

Chemotherapy is the treatment that utilizes cytotoxic drugs (drugs toxic to cells) to stop the proliferation of the cancerous cells or to destroy them. Unlike radiation therapy or surgery, which work on particular cancerous regions, chemotherapy works on a systematic basis, and it doesn’t matter to the cancer patients where the cancer cells are hiding in their bodies.

What Does Chemotherapy Do in the Body?

Chemotherapy drugs work by interfering with the ability of cancer cells to grow and divide. In contrast to normal cells, cancer cells grow at a much faster rate. Thus, faster multiplying cancer cells are especially vulnerable to these drugs.

Chemotherapy targets both the damage to the cells’ DNA and the process of cell division in the cell cycle. It attempts to stop the uncontrolled growth by targeting various stages of the cycle.

However, chemotherapy doesn’t distinguish perfectly between cancerous and healthy cells. As a result, normal cells that also divide rapidly, such as those in the gastrointestinal tract lining, hair follicles, bone marrow, and reproductive organs, can be affected. This is why side effects such as fatigue, nausea, hair loss, and an increased risk of infection are common during treatment.

The mechanism by which chemotherapy works in the body varies depending on the type of cancer being treated and the type of drugs used. Some drugs circulate through the bloodstream and attack cancer cells throughout the body (systemic therapy), while others are delivered directly into a body cavity or organ for more localized treatment.

The primary goals of chemotherapy include:

• Curing cancer (when possible): In certain cancers, especially when detected early, chemotherapy can eliminate all cancer cells, resulting in complete remission and potentially curing the disease.
• Controlling tumor growth: When a cure isn’t possible, chemotherapy can slow the progression of the disease, shrink tumors, and stop the cancer from spreading further.
• Palliating symptoms in advanced stages: In late-stage or metastatic cancer, chemotherapy may not cure the disease but can significantly reduce symptoms such as pain, pressure, or bleeding, improving the patient’s quality of life.

The effectiveness of chemotherapy depends on several factors, including the type and stage of cancer, the specific drugs used, and the patient’s overall health. Oncologists carefully tailor each treatment plan to maximize benefit while managing potential risks.

At What Stage of Cancer Is Chemotherapy Used?

Chemotherapy plays a versatile role in cancer treatment. It can be administered at nearly every stage of the disease, depending on the type of cancer, its location, the extent of its spread (metastases), as well as the patient’s general condition and fitness level.
Here’s how it fits into different phases of the cancer journey:

• Before surgery to shrink tumors (neoadjuvant chemotherapy): In specific types of cancer, it is possible to use chemotherapy before surgery to reduce the volume of the tumor. It is also possible to improve the chance of preserving healthy tissue, which is essential in the surgery for cancer of the breast, rectum, and esophagus.
• After surgery to eliminate remaining cells (adjuvant chemotherapy), following successful tumor removal, microscopic cancer cells may still be present in the body. Adjuvant chemotherapy is used post-surgery to kill these residual cells and reduce the risk of cancer recurrence. This is common in breast, colon, and lung cancers.
• As a primary treatment for cancers that aren’t surgically removable: Among these cancers, such as certain types of leukemia, lymphoma, or advanced-stage solid tumors, cannot be treated effectively with surgery. For these categories of patients, chemotherapy is the gold standard for controlling the underlying disease and prolonging survival.
• For symptom relief in late-stage cancers (palliative care): When cancer has spread widely and a cure is no longer possible, chemotherapy may still be used to shrink tumors, slow disease progression, and relieve symptoms such as pain, pressure, or difficulty breathing. This approach focuses on improving quality of life rather than curing the disease.

Types of Chemotherapy Treatments

Traditional IV Chemotherapy

The most common method, intravenous (IV) chemo, involves inserting a catheter into a vein (sometimes through a chemotherapy port) to deliver the drug directly into the bloodstream.

Oral Chemotherapy: Pills vs IV

Some chemotherapy drugs are now available in pill or capsule form, offering a convenient option for certain types of cancer. While easier to take, oral chemotherapy still requires close monitoring due to side effects and potential interactions (Medical News Today, 2024).

Chemotherapy Cream for Skin Cancer

For certain types of skin cancer, such as superficial basal cell carcinoma, doctors may prescribe a chemotherapy cream, like 5-fluorouracil (5-FU), which is applied directly to the skin.

Intraperitoneal Chemotherapy for Abdominal Cancers

This involves delivering chemotherapy directly into the abdominal cavity, which is often used for ovarian or peritoneal cancers. It can provide higher local drug concentrations with fewer systemic side effects.

How Is Chemotherapy Administered?

Chemotherapy can be delivered in several ways, but the chemotherapy process usually follows a carefully planned cycle that allows the body time to recover between treatments. The method and schedule depend on the type of cancer, the specific chemotherapy drugs used, and the patient’s health profile.

The Chemotherapy Process Step-by-Step

Here’s what typically happens during a standard chemotherapy cycle:

• Assessment and blood work: Before each session, your medical team will conduct a comprehensive health assessment through a physical exam and laboratory tests, with a particular focus on blood counts.
  This helps determine if it’s safe to proceed with treatment or if adjustments are needed. Low white blood cell counts, for example, could delay treatment due to an increased risk of infection.
• Pre-medication to prevent nausea or allergic reactions: You’ll likely receive medications before chemotherapy starts to help minimize side effects.
  These often include anti-nausea drugs, steroids, and sometimes antihistamines, especially if your regimen involves medicines known to cause allergic reactions.
• Drug infusion or oral administration: Chemotherapy can be given in several forms:
  
  • Intravenous (IV) infusion: The most common method, where drugs are delivered through a vein, either via a temporary IV line or a long-term chemotherapy port.
  • Oral chemotherapy: Pills or capsules taken by mouth, which offer flexibility but still require close monitoring.
  • Injection: Some drugs are injected directly into muscles, under the skin, or into body cavities like the spinal fluid or abdominal area.
  • Topical application: In specific cases, such as skin cancer, a chemotherapy cream may be applied directly to the affected area.

Each session may last from a few minutes to several hours, depending on the drug protocol.

• Monitoring for immediate side effects: During and after drug administration, nurses and oncologists will observe you for reactions like fever, nausea, dizziness, or allergic responses. Vital signs are checked regularly, and emergency medications are on hand if needed.
• Rest period before the next cycle: Chemotherapy is typically administered in cycles, periods of treatment followed by a rest phase. The rest period allows your healthy cells to recover and helps manage side effects. 

A typical cycle may be weekly, bi-weekly, or every three weeks, and the whole course could involve multiple cycles over several months.

What Is a Chemotherapy Port?

A chemo port is a small medical device implanted under the skin to provide easy access to veins. It’s beneficial for patients requiring long-term treatment.

Is Chemotherapy Painful? What to Expect

The chemotherapy infusion process itself is typically not painful. Most patients describe it as similar to getting a routine IV or blood draw. A needle or catheter is inserted into a vein, usually in the arm or through a chemotherapy port, to deliver the medication. 

However, some individuals may experience a mild burning or stinging sensation at the injection site, especially if the drugs are irritating to the veins. This is known as vein irritation or phlebitis, and nurses closely monitor for it during the infusion process.

The majority of discomfort associated with chemotherapy arises after the treatment, due to side effects caused by the drugs’ impact on healthy, fast-dividing cells. These side effects can vary widely based on:

• The type of chemotherapy drugs used
• The dose and frequency
  
• Your individual tolerance and health status

Severe pain is not a typical feature of chemotherapy itself, but complications such as nerve damage, infections, or reactions to the drugs may cause significant discomfort in some patients. 

Common Side Effects of Chemotherapy

What Are the Side Effects of Chemotherapy?

Some of the most common include:

• Fatigue
• Nausea and vomiting
• Hair loss
• Mouth sores
• Low blood cell counts (leading to infection risk)
• Diarrhea or constipation

Does Chemotherapy Cause Hair Loss?

Yes, many chemotherapy drugs can cause hair loss because they target rapidly dividing cells, including not only cancer cells but also healthy cells, such as those in the hair follicles. Hair follicles are among the fastest-growing cells in the body, which makes them particularly vulnerable to the effects of chemotherapy.

Hair loss typically begins 2 to 4 weeks after starting treatment and may progress gradually or suddenly, depending on the type and dosage of chemotherapy used.

 It can occur on the scalp, eyebrows, eyelashes, arms, legs, and other parts of the body. Not all chemotherapy drugs cause hair loss, and the severity of the loss can vary from person to person.

Although the experience of losing hair can be emotionally distressing, it’s essential to remember that in most cases, hair regrows after chemotherapy is completed. Regrowth often begins within a few weeks to months after the last treatment session, and the new hair may initially have a different texture or color.

To help manage or reduce hair loss, some patients use scalp cooling caps during treatment, which may decrease blood flow to the scalp and reduce the amount of chemotherapy that reaches hair follicles. While not effective for everyone, cooling caps have shown promising results in clinical studies.

How to Minimize Chemotherapy Side Effects

To help patients cope with the wide range of chemotherapy side effects, doctors often implement supportive measures tailored to the individual’s treatment plan and overall health. These interventions can significantly improve the quality of life during treatment.

• Anti-nausea meds: Chemotherapy-induced nausea and vomiting (CINV) are common and can interfere with nutrition and daily function. Doctors may prescribe antiemetic medications to prevent or control nausea before it begins.
• Growth factors to boost white blood cells: Since chemotherapy often suppresses bone marrow function, patients may develop neutropenia, a dangerous drop in white blood cell count. To reduce the risk of infection, oncologists may recommend colony-stimulating factors, such as filgrastim or pegfilgrastim, which stimulate the bone marrow to produce more white blood cells.
• Exercise and diet adjustments to support immune function: Engaging in mild to moderate physical activity, such as walking or yoga, has been shown to reduce fatigue and improve circulation.
  Meanwhile, a balanced diet rich in lean proteins, whole grains, and antioxidants can help strengthen the immune system and promote overall well-being and healing.

Dietitians and physical therapists often play a crucial role in tailoring these lifestyle strategies to meet a patient’s specific needs.

Long-Term Effects and Recovery

Some side effects of chemotherapy don’t end when treatment does. Depending on the drugs used and the individual’s response, specific effects may last for months or even become permanent:

• Neuropathy: Tingling, numbness, or pain in the hands and feet (called peripheral neuropathy) can result from nerve damage caused by specific chemotherapy agents.
• Fertility issues: Some chemotherapy drugs can affect reproductive organs, potentially leading to temporary or permanent infertility. Fertility preservation discussions are encouraged to begin before treatment commences.
• Fatigue: Cancer-related fatigue may linger even after treatment has ended. It is often multifactorial, linked to anemia, stress, nutritional deficits, or other long-term effects.

Advanced Chemotherapy Options

Neoadjuvant vs Adjuvant Chemotherapy

• Neoadjuvant: Before surgery, to reduce tumor size
• Adjuvant: After surgery, to eliminate microscopic cancer cells

Mesothelioma Chemotherapy Specifics

Mesothelioma, a rare cancer caused by asbestos exposure, often requires a combination of cisplatin and pemetrexed, delivered systemically or intrapleurally.

Breast Cancer Chemotherapy Overview

Breast cancer treatment may involve:

• Taxanes (like paclitaxel)
• Anthracyclines
• Tailored regimens based on cancer subtype (Medical News Today, 2024)

Comparing Chemotherapy With Other Cancer Treatments

Immunotherapy vs Chemotherapy

• Chemotherapy kills cancer cells directly.
• Immunotherapy enhances your immune system’s ability to fight cancer.
  Immunotherapy may cause fewer systemic side effects but isn’t effective for all cancers.

Radiotherapy vs Chemotherapy

• Radiotherapy targets specific areas with high-energy rays.
• Chemotherapy is systemic.
  They’re often used together for enhanced effect.

Are There Alternatives to Chemotherapy?

Some cancers respond to:

• Targeted therapy
• Hormone therapy
• Immunotherapy
  Your oncologist determines the best approach based on the type and stage of your cancer.

Daily Life & Safety During Chemotherapy

Things Not to Do While on Chemotherapy

Avoid:

• Smoking or alcohol
• Large crowds (due to infection risk)
• Raw or undercooked food
• Overexertion or stress

Chemotherapy Precautions for Family Members at Home

Family members should wear gloves when handling bodily fluids (such as laundry and vomit) and follow proper hygiene protocols during the first 48 hours after chemotherapy.

How to Control Blood Sugar and Eat Right During Chemotherapy

Stick to:

• Small, frequent meals
• Low-glycemic foods
• Plenty of hydration: Dietitians often help tailor plans during treatment.

Exercise and Physical Activity Tips

Moderate exercise, such as walking or light yoga, may reduce fatigue and preserve nerve function during treatment.

Financial & Logistical Considerations

Chemotherapy Cost & Insurance Coverage

Costs vary widely based on:

• Drug type
• Number of cycles

Country/region
Most insurance plans cover chemotherapy, but out-of-pocket expenses can be significant.

Parting Thoughts: Staying Informed and Empowered

Chemotherapy remains one of the most essential tools in the fight against cancer. While it presents challenges, understanding the process can help alleviate fear and enable patients to make more informed decisions. If you or a loved one is navigating cancer treatment, speak with your oncologist and care team about all your options and lean on support networks for strength and clarity.

Reference

Medical News Today. (2024). Oral Chemotherapy for Breast Cancer.
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Cancer Center. (2023). Chemotherapy Facts and Myths.
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Medical News Today. (2024). Exercise and Chemotherapy.
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American Cancer Society. (2024). Understanding Chemotherapy.
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Mayo Clinic. (2024). Hair loss from chemotherapy.
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Cleveland Clinic. (2023). Chemotherapy Side Effects.
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