Body Changes with Cancer Treatment

teresaamadrigal
May 15, 2025
3 min read

Updated: Jun 4, 2025

What Happens to Your Body During and After Cancer Treatment?

If you or someone you love is getting ready for cancer treatment, you might be wondering: What’s going to happen to my body? It’s a great question, and you’re not alone. Let’s walk through what can change before and after treatment, especially in your lymphatic system, immune response, and muscle/nerve function and how you can take care of yourself along the way.

Interstitial Fluid: One Of The Body’s Many Hero's

Before we get into the nuts and bolts of treatment effects, let’s talk about interstitial fluid, that watery cushion that fills the spaces between your cells. It’s like the delivery truck for your cells: it carries water, salts, glucose, amino acids, hormones, and other nutrients, while also picking up waste products. This fluid comes from blood plasma and eventually gets reabsorbed by your lymphatic system, like a recycling plant. It helps prevent dehydration, supplies oxygen to cells, transports hormones and immune cells, keeps your electrolytes balanced, and supports your organs and tissues.

What Can You Do? Physical activity, such as exercise, can increase lymph flow, which helps to move fluid back into the bloodstream. Posture can also impact fluid movement, with standing potentially leading to a decrease in lymph flow from the lower extremities.

The Lymphatic System: Your Body’s Drainage Network

Before Treatment: Your lymphatic system is a one way drainage highway that collects interstitial fluid, waste, and even fats from your tissues.

Along the way, lymph passes through:

Lymphatic capillaries (tiny, closed-end vessels that collect fluid)
Larger lymphatic vessels (valved, to keep fluid moving one way)
Collecting ducts (the thoracic duct and right lymphatic duct) that finally drain lymph into your veins in the chest

After Treatment: If you’ve had surgery or radiation, your lymphatic system might not drain as well, leading to swelling (lymphedema). Fluid might build up in your arms, legs, or other areas depending on the treatment site.

What Can You Do? Gentle exercise, compression garments, and massage therapy can help keep lymph moving and prevent swelling.

The Immune System: Your Body’s Defense Force

Before Treatment: Your immune system (like a big security team) detects and attacks infections and cancer cells. Lymph nodes, full of lymphocytes (white blood cells), act as checkpoints that filter lymph and jump an immune response if needed.

After Treatment:

Chemotherapy and radiation can slow down your immune system, making infections easier to catch.

Immunotherapies can speed up the immune system, sometimes causing it to attack healthy tissues too.

What Can You Do? Wash your hands often, ask about vaccines, and let your doctor know right away if you have a fever or feel sick.

Muscles and Nerves: Feeling the Signals

Before Treatment: Your muscles and nerves normally work together like a team. Nerves send electrical and chemical signals to your muscles, telling them when and how to move.

After Treatment:

Chemotherapy can cause peripheral neuropathy, a tingling or burning feeling in your hands and feet.

Radiation can stiffen tissues and affect nearby nerves, leading to pain or weakness.

Surgery might damage nerves in the treatment area, sometimes leading to coordination problems or muscle weakness.

Chemical signaling can also be disrupted; treatments might interfere with neurotransmitters (the chemical messengers nerves use to communicate with muscles), leading to fatigue, weakness, or difficulty with fine motor skills.

What Can You Do? Staying active (walking or stretching) and working with a physical therapist can help keep muscles strong and reduce stiffness. Let your care team know if you notice any numbness, pain, or weakness and they can suggest medications or therapies to manage these symptoms.