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Understanding the lymphatic system and cancer treatment

Updated: 3 days ago

Our physiotherapist Hannah summarises the lymphatic system and how it can be affected by cancer treatment.

What is the lymphatic system?

Our lymphatic system is important, complex and often overlooked, compared to the better known circulatory system! It is a network of organs, tissues and delicate vessels spread throughout the body, which moves lymph fluid (colourless and watery in appearance) from our tissues and empties it back into the bloodstream via the lymph nodes.

The three main role of the lymphatic system is:

  • To maintain the balance of fluid level in the body

  • To protect the body against infection, as part of our immune system

  • To help move certain fats from our bowel into the bloodstream (Ozdowski and Gupta, 2023)

Every day, around 20 litres of plasma (the liquid part of our blood) move through tiny pores in the thin wall of our capillaries and into the surrounding tissues. Imagine this like water slowly seeping out of a sponge. This important fluid delivers oxygen and nutrients to the tissues, which absorb as much as they need and leave the rest as waste. Next, our plasma fluid collects the waste products and returns to our bloodstream - a total of about 17 litres a day! This means there are around 3 litres of plasma fluid and waste remaining in our tissues, outside of our blood stream; this excess plasma fluid becomes known as lymph fluid.

Our lymphatic capillaries collect the lymph fluid from the tissues and move into network of larger tubes (lymphatic vessels) and does (lymph nodes, see below), towards one of two major ducts in the upper chest; the lymphatic duct which channels 25% of our lymphatic fluid and the thoracic duct which channels the other 75%. From here, the ducts merge into deep, major veins (subclavian veins) where the lymph fluid can re-enter the bloodstream. Our lymphatic vessels contain one-way valves to prevent lymphatic fluid from moving in the wrong direction.

Image of lymphatic system
Lymphatic system

Image from: Cardiovascular Pathology (Fourth Edition), 2016

Important components of our lymphatic system are:

  • Bone marrow: The soft, spongy centre of certain bones, which produce white blood cells, red blood cells and platelets; this is an important part of our immune system.

  • Thymus: An organ located in the upper chest beneath the breast bone, where our T-cells (a type of white blood cell that prevents infection) fully mature.

  • Lymph nodes: Bean-shaped glands that filter lymph fluid as it passes through them (around 600 in body, found in chains in areas such as armpoint, groin and neck). These glands remove damaged cells and store lymphocytes (cells that destroy harmful substances like bacteria).

  • Spleen: Our largest lymphatic organ, located under the left side of our ribs and above our stomach, which filters our blood and removes unwanted cells. It also stores additional red blood cells and platelets, for when the body requires them.

What is lymphoedema?

Lymphoedema is the excessive build-up of lymph fluid which causes swelling in an area of the body, commonly in the arms or legs, although it can also be found in the chest, abdomen, genitals, pelvis, head, neck, face, breast and armpit.

Our lymphatic system is similar to our blood system, in that it carries an important fluid around the body through a network of vessels. One of the most important structural differences is that the lymphatic system does not have a single pump (such as the heart) and movement of lymph fluid is reliant on changes to position and internal pressure (such as muscle contraction, gravity, deep breathing, pulsing from blood vessels).

Damage or blockages within any component of the lymphatic system may prevent fluid from moving through vessels and nodes into the main ducts, therefore it cannot be returned into the bloodstream and results in a build-up of excessive lymph fluid in our tissues known as lymphoedema.

What increases the risk of lymphoedema?

As mentioned above, lymphoedema may occur when there is direct physical damage to the lymphatic system or when the system is physically blocked by an external factor.

Examples of this may include:

  • Tumours in areas that can block lymphatic vessels, such as near the groin or armpit.

  • Removal of lymph nodes, particularly inguinal (groin) lymph node clearance and axillary (armpit) lymph node clearance; it is less common following sentinel lymph node biopsy, due to a reduced number of affected nodes.

  • Damage to the lymphatic vessels, following surgery or radiotherapy.

  • Infection (in an area of compromised lymphatic health)

  • Damage to lymphatic vessels from trauma or injury

  • Reduced walking and physical activity

  • Medical issues with veins, such as varicose veins or blood clots

  • Obesity (due to risk of pressure on and obstruction of lymphatic vessels).

How can I support my general lymphatic health?

Fortunately, there are many holistic actions we can take to support our general lymphatic health, such as:

  • Regular physical activity and movement (150 minutes of moderate activity a week)

  • Maintaining a regular skin care routine (clean, moisturised, unbroken skin).

  • Regular deep breathing exercises

  • Manual lymphatic drainage techniques

  • Positioning for lymphatic drainage (elevating limbs to allow gravity to move fluid towards the centre of body)

  • Maintaining a healthy weight

  • Compression therapy, as directed by a specialist

  • Kinesiotaping, as directed by a specialist

What is important about physical activity?

Staying physically active is an essential part of supporting our lymphatic system. When we are physically active, we increase the amount of muscle contraction and blood circulation around our body, which can assist with the movement of lymphatic fluid from our tissues back into our bloodstream. It also helps to prevent blood clots, which can affect both our circulatory and lymphatic systems and may cause other serious issues such as DVT, pulmonary embolism or a stroke.

While staying active is essential, there are some things to be mindful of when exercises, such as:

  • Minimising the risk of trauma; certain activities such as contact sports or horse riding, carry a higher risk of injury which may damage or overwhelm a compromised lymphatic system.

  • Minimise injection risks where possible; for example, swimming in a public pool with open cuts.

  • Common advice to avoid maintaining static holds, such as planks, due to the increased strain on the lymphatic system and risk of increasing swelling; there is no specific guidance or good quality evidence at this time to support this advice. If you are at high risk of lymphoedema, consider alternatives to static holds, such as moving through plank into another position.

If you are unsure about exercising safely, then it is important to speak with a qualified health professional, or email me at

What is important about skin care?

If you are someone who has a compromised lymphatic system following cancer treatment, it is essential to minimise risk of infection. Developing an infection in a specific area will trigger the body to send increased numbers of white blood cells in plasma fluid, which in turn increases the waste products and lymph fluid. If the lymphatic system in this area is damaged or blocked, the increased amount of lymph fluid will be difficult to move and result in fluid build-up and swelling in the area.

Good skin care will help minimise risk of localised infection and can include:

  • Keeping skin unbroken and well moisturised (emollient).

  • Avoiding injury and cuts in affected areas

  • If skin is broken, clean and cover immediately.

  • Wearing sun protection daily and covering skin where possible.

  • Using insect repellent and avoid scratching bites

  • Keeping nails clean and short

  • Opting for injections, blood tests and blood pressure cuffs on unaffected arm; although NICE (2024) highlights there is no good quality evidence to show this increases risk of lymphoedema.

  • Wearing gardening gloves or oven gloves to avoid burns and injury

  • Avoiding particularly tight jewellery and clothing, as this may obstruct lymphatic drainage

What is lymphatic drainage?

Lymphatic drainage is a process of using external pressure to physically move and drainage fluid from one area of the body to another - usually from an area of congestion towards a collection of functioning lymph nodes.

There are two types of lymphatic drainage:

  • Manual Lymph Drainage can be carried out by a specialist lymphoedema practioner, to help promote lymph drainage and manage lymphoedema.

  • Simple Lymph Drainage are more simple techniques that yourself or a loved one can practise daily, taking around 20 minutes. These techniques can be taught by a specialist practitioner or through trusted resources online (I would recommend these YouTube videos by Cancer Rehab PT).

Should I avoid hot temperatures?

Historically, advice has always been for those at risk of lymphoedema to avoid extreme temperatures - such as hot tubs - as it was thought to intensify lymphatic load and the risk of swelling. However, recent evidence contradicts this advice.

Hill et al (2023) completed a systematic review of 1137 people with lymphoedema, using a form of heat therapy (20 modalities including microwave, hot water, light therapy, electric blanket, infrared and ultrasound). Overall, studies found a reduction in limb volume/circumference from baseline to end of study and adverse effects were rare.

The current evidence-base suggests that heat therapy may help in reducing limb circumference and limb volume when provided over a long period of time (1200–3600 min) at a specific skin temperature (39–42 °C) in a controlled environment (laboratory/hospital/outpatients) in lower limb lymphoedema.

While no specific clinical recommendation can yet be made, it challenges our previous understanding of the relationship between heat and lymphoedema.


There are many things that we can do to help support general lymphatic health. These habits and lifestyle choices can be even more important for those who are at risk of lymphoedema following cancer treatment.

The links below provide further sources of information and support:

If you are unsure what is the best advice for you, I would encourage you to speak with your oncology team or get in touch with me at for further support and signposting.


  • Hill, J. E., Whitaker, J. C., Sharafi, N., Hamer, O., Chohan, A., Harris, C., & Clegg, A. (2023). The effectiveness and safety of heat/cold therapy in adults with lymphoedema: systematic review. Disability and Rehabilitation, 1–12.

  • National Institute of Health and Care Excellence (2024) Early and Locally Advanced Breast Cancer Diagnosis and Management [NICE Guideline NG101]

  • Ozdowski, L., & Gupta, V. (2023). Physiology, Lymphatic System. In StatPearls. StatPearls Publishing.

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