I heard that moles on the soles of feet are prone to become malignant. Is it true or false?

If you spend a lot of time on the Internet, you may see a lot of things. For example, I believe many people have heard a saying - if you have a mole on the sole of the foot, you must remove it. If you want to know why, it is because moles on the sole of the foot are prone to malignant transformation, or in other words, moles are prone to malignant transformation after friction. The implication is that moles on the sole of the foot are prone to malignant transformation into melanoma, and must be removed in advance for prevention.

So, is this statement true or false?

Image source: Tuchong Creative

To simply answer this question, this statement is unreliable and blindly removing moles is not recommended.

If you want to answer this in detail, you need to discuss it. If you are interested, please continue reading.

1. The overall risk of a mole becoming malignant is very small

After reading too much information online, we tend to fall into a misunderstanding, which is to exaggerate the probability of bad things happening, such as worrying too much about moles becoming malignant.

Common moles exist on almost every one of us, and their incidence in the population is close to 100%.

The incidence of malignant melanoma in the population is much lower, not 1%, not 0.01%, not 0.001%, but 0.0009%, which means that on average only 9 people out of 1 million will get melanoma. This data comes from the academic work "China Melanoma Standardized Diagnosis and Treatment Quality Control Indicators (2022 Edition)" recently released by the Melanoma Quality Control Expert Committee of the National Cancer Quality Control Center.

It is easy to see from the data that the overall risk of a mole becoming malignant is very small. The probability of 9 in 1 million is almost comparable to winning the lottery jackpot, becoming a world champion or Olympic gold medalist, or experiencing two car accidents in a short period of time.

2. Friction is not necessarily a risk factor for malignant transformation of moles

Another misunderstanding is that many of us take daily friction too seriously, and even think it is a common sense of health. In fact, friction does not necessarily accelerate the malignant transformation of moles.

There is a lot of evidence for this:

So far, there is not enough evidence to conclude that mechanical friction can cause or accelerate malignant changes.

The mainstream risk factors for malignant transformation of moles do not include mechanical friction;

It has also not been observed that moles on the soles of the feet are more likely to become malignant than moles on other parts of the body;

Moles on other parts of the skin will also experience friction, such as the hands, face, and scalp. Frequent friction is inevitable when using hands, washing face, and combing hair.

3. The risk factors that need attention are as follows

Some of the more important and critical risk factors are long-term strong sun exposure, repeated severe sunburns in childhood, frequent sunbathing, too many moles (50 to 100 or even more), personal or family history of melanoma, and people with very white skin (similar to Caucasians).

It can be seen that excessive sun exposure is actually bad for the skin (presumably for people who have little or no sun exposure). The main reason for this is the effect of ultraviolet rays in sunlight. Ultraviolet rays can directly damage the DNA structure of skin cells, causing DNA damage. If this damage accumulates too much, it may cause cell mutations, and then cancer cells may appear.

In addition, long-term and intense sunlight exposure can cause damage to the skin tissue structure, leading to skin aging, elastic fiber destruction and collagen degradation, thereby increasing the incidence of skin cancer (including melanoma).

To reduce this risk, you can take the following precautions:

Avoid prolonged exposure to the sun;

Wear appropriate sun-protective clothing and provide physical protection;

Use sunscreen on exposed skin;

Wear sunglasses to protect your eyes.

4. Regular observation is better than blind resection

The more mainstream academic view is that most of these moles that grow slowly after birth are basically benign throughout life, and the risk of malignancy is very similar, so there is basically no need to remove the moles preventively.

These common moles have their own changing process. For example, the number of moles will begin to increase during childhood and adolescence, reach a peak in the 20s, and then slowly fade away with age. Even among children and adolescents, some moles can naturally grow larger or become raised.

In addition, there is another point of knowledge - even for melanoma, about 2/3 of it actually grows from normal skin, and only 1/3 of melanoma comes from pre-existing moles. So, don't be afraid of moles, in many cases you just need to observe them.

So how do you observe yourself?

A relatively simple way is to use the mainstream ABCDE rules at home and abroad to make a preliminary judgment.

This ABCDE is a combination of the first letters of five English words, namely:

A stands for asymmetry in appearance. The mole is not round or oval. If you draw a line through the middle, the appearances of the two sides are different.

B: The border has changed and become irregular, unclear or fan-shaped;

C stands for multiple changes of color. It is no longer a simple color. Different areas have different colors. Red, white, black, brown, and blue can all appear.

D stands for the diameter. Generally, the diameter of a mole after birth is less than 5 mm. If the diameter is larger than 6 mm, you should pay attention to it.

E stands for evolving, which means that the mole looks different from other moles on the body, such as changes in size, shape, and color.

If you find that a mole on your body (whether on your feet or other parts) has some changes in the ABCDE rule, or if you find it difficult to judge, you can see a doctor for further evaluation, such as asking about the mole, looking at the appearance of the mole, and doing individual examinations. If the mole has not changed and is very stable, you can continue to observe it.

Finally, I would like to emphasize a few details that need to be paid attention to when using the ABCDE rule. Don't assume that compliance with the rule means a change for the worse, for example:

If the mole is present at birth or a few weeks after birth, we consider it a congenital pigmented nevus. It is not appropriate to refer to this rule when evaluating it (it is not very valuable for reference). It is more important for the doctor to evaluate it.

Normal moles can also change easily during pregnancy, such as growing larger or darkening. This is common during pregnancy and is almost never a sign of malignancy, so don’t worry too much.

The ABCDE rule is only a preliminary screening method and cannot be used for diagnosis. It does not mean that melanoma can be diagnosed if all the letters are met. Even if all the letters are met, many are not melanomas or even moles, but other benign skin lesions that are misdiagnosed as moles.

Well, that’s all for today’s sharing. Now, what do you think about having moles?

The article is produced by Science Popularization China-Starry Sky Project (Creation and Cultivation). Please indicate the source when reprinting.

Author: Tang Jiaoqing, attending physician of dermatology, doctor of medicine, popular science author

Reviewer: Cheng Fang, Chief Physician, Department of Dermatology, Xingtai People's Hospital, Hebei Province