Finger clubbing, which includes swelling of the fingertips and changes to the appearance of fingernails, is a common symptom of lung cancer. Around 80 percent of people with finger clubbing have lung cancer. Sometimes called “clubbed fingers” or “digital clubbing,” finger clubbing may run in families as a harmless trait. It may also be an indication of heart, liver, or other lung disorders.

Finger clubbing is generally not one of the early symptoms of lung cancer, though for some people, it may be among the first noticeable ones. Symptoms of lung cancer usually show up only in later stages as the condition progresses. For this reason, it’s important to talk to your health care provider right away if you do notice potential early signs and symptoms of lung cancer.

This article will cover what finger clubbing looks like, its causes, and when to see your health care provider.

What Does Finger Clubbing Look Like?

People with finger clubbing may have:

• Bulging fingertips
• Soft nail beds with fingernails that don’t look firmly attached
• Fingernails that angle sharply at the cuticle (base of the fingernail)
• Fingernails that curve downward around the fingertips

Finger clubbing usually develops slowly, so you may not initially notice it’s happening. If you do see anything early on, it may be reddening and softening of the nail bed (the soft skin underneath your nails). If you touch your nails, they might also feel spongy.

Eventually, your nails will have a downward curve and a shiny appearance. You can tell apart normally curved nails vs. clubbed nails because clubbed nails have a very noticeable spoon-shaped curve at the ends of the fingers. You might also notice an enlargement of your fingertips.

What Causes Finger Clubbing?

The most common cause of clubbing is lung cancer. However, like most symptoms of lung cancer, clubbed fingers may not show up in the early stages of the disease. Rather, they’ll develop once the condition has progressed into the later stages.

Finger clubbing may be linked to low oxygen, which can occur in lung cancer and other conditions. In lung cancer, finger clubbing is thought to be associated with excessive amounts of growth factors that encourage the growth of blood vessels.

Additionally, some lung cancer treatments and comorbidities (other health conditions you may have at the same time) can also contribute to nail or finger changes.

Lung Cancer Treatments and Finger Clubbing

Some lung cancer treatments may cause nail or finger changes. Some of these may look similar to finger clubbing, but they’re not symptoms of finger clubbing.

The following medications used to treat lung cancer can cause nail changes and swelling of your fingertips:

• Afatinib (Gilotrif)
• Albumin-bound paclitaxel (Abraxane)
• Cisplatin
• Docetaxel (Taxotere)
• Doxorubicin
• Erlotinib
• Gemcitabine (Gemzar)
• Osimertinib (Tagrisso)
• Paclitaxel

Read more about specific medications and side effects in this list of treatments for lung cancer.

Lung Cancer Comorbidities and Finger Clubbing

Some comorbidities of lung cancer are linked to clubbed fingers, including:

• Chronic lung infections, such as bronchiectasis or cystic fibrosis
• Other infections, such as HIV and hepatitis B or C
• Liver disease, such as cirrhosis of the liver
• Other cancers, such as liver cancer or Hodgkin lymphoma, a type of blood cancer

Other nail changes that can occur due to cancer or cancer treatments include:

• Thin cracks, tears, or deep cuts in the nail or fingertip
• Lines or ridges on the nail
• Discoloration or swelling around the nail
• Loss of a nail
• Darkening near the cuticle (at the base of the nail) or the whole nail
• Bleeding under the nail, shown by red lines
• Lifting of the nail from the nail bed

Although less common, skin symptoms can also be a sign of lung cancer or a result of skin cancer treatment, such as rash after radiation or chemotherapy.

Finger or Thumb Test

Because clubbed fingers can take many years to develop, it may be hard to notice at first. Doing a finger or thumb test for lung cancer can help you spot changes. You can check for the Schamroth sign to see if your fingers have become clubbed.

Checking for the Schamroth sign entails placing the nails of both index fingers together up to the last joint as if you’re forming the top of a heart shape. You should be able to see a diamond-shaped window of space form between your nails and the joints closest to your fingertips. If you don’t see this space, then you might have finger clubbing.

Is There Treatment for Nail Clubbing?

Clubbing of the fingers can be a temporary or long-term symptom depending on what’s causing it. If it’s caused by a health condition, treating the condition may reverse the finger clubbing. If finger clubbing is the result of a chronic condition or cancer, clubbing may be long term or permanent.

As such, nail clubbing due to lung cancer likely won’t go away. Nail clubbing, on its own, doesn’t need to be treated. Instead, your doctor will focus on treating the cancer or other underlying condition causing nail clubbing.

What Does Finger Clubbing Tell Your Health Care Provider?

Clubbed fingers typically don’t require treatment, but it’s a good idea to let your health care provider know if you develop this symptom because clubbed fingers can be connected to serious medical conditions.

Changes you should tell your health provider about include a downward curve in your fingernails and swelling in your fingertips. After examining your fingers, your doctor may ask about other symptoms. They also may order some blood and lab tests to diagnose or rule out health conditions that may be causing clubbed fingers.

Talk With Others Who Understand

MyLungCancerTeam is the social network for people with lung cancer and their loved ones. On MyLungCancerTeam, more than 12,000 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

Do you have clubbed fingers related to lung cancer? Did they occur along with other lung cancer symptoms like chest pain or shortness of breath? Share your experience in the comments below, or start a conversation by posting on your Activities page.