The term skin cancer is an umbrella term for various cancers of the skin which can have many different manifestations. A distinction is made between non-melanoma skin cancer and malignant melanoma.
For the past few decades, skin cancer has been occurring more and more frequently: Every year, two to three million new cases of non-melanoma skin cancer and more than 130,000 new cases of malignant melanoma are first diagnosed worldwide. Sections of the population with a light skin type often exposed to sunlight are particularly affected.
During the tanning process, the skin tries to protect itself from the strength of the sun’s radiation. This is not always possible and can result in painful sunburn. The long-time effects of this are even worse. Purely on the surface, the skin recovers reasonably quickly from sunburn. However, deep inside the skin the excessive sunbathing session has left indelible marks: Similar to radioactive radiation, UV radiation causes damage to the DNA. This damage can be the starting point for an uncontrolled proliferation of mutated body cells. These mutated body cells can cause cancer.
Malignant melanoma is a malignant tumour which can develop from a mutation of the pigment-containing cells. Initially there is an increase in cell division during which the cells become less and less differentiated. From this cell growth a tumour develops which quickly spreads throughout the body.
If melanoma is detected early, all types have a very good prognosis in principle. In case of metastasis the prognosis is very poor.
Skin cancer rates have been rising sharply for years. People tend to expose their skin to too much UV light. With basic knowledge of the sun’s radiation, protection from the sun and how to deal correctly with UV light it is still possible though to enjoy sunshine safely.
The following sections of the population are at an inherently greater risk:
- a high number of moles
- blonde or red hair, blue eyes, freckles
- family history of melanoma
Additional external risk factors include:
- intensive, repeated sunbathing
- 5 and more painful sunburns before the age of 15
- Use of indoor tanning beds
For skin cancer prevention it is important to use a sunscreen with a sun protection factor suitable to the respective intensity of the sunlight. Sunbathing without sunscreen should be avoided.
Children’s skin in particular is so sensitive that physicians advise the use of sun protective clothing.
As part of the skin cancer screening offered by the state, people over the age of 35 can have their doctor check their skin and moles every two years.
Regular self-examinations of the skin can help detect skin changes and any moles that have grown in size early on.
The ABCDE mnemonic is helpful for visual screening:
- Borders (irregular)
- Colour (variegated)
- Diameter (greater than 5 mm)
- Elevation, steps towards the edges
Additional changes should be seen by a doctor:
- Increase in size
- Change to the shape of existing moles
- Bleeding mole
How is melanoma treated?
In terms of prognosis, it is crucial that the melanoma is removed in time. The choice of the best treatment option depends on the individual circumstances and different factors and needs to be decided by the physician together with the patient.
Different types of therapy are available for treating melanoma:
Malignant melanoma needs to be removed completely with surgery. The extent of the surgery depends on the thickness of the tumour as determined histologically.
If the tumour is thicker than one millimetre, the first lymph nodes in the lymphatic flow of the affected skin region should be removed surgically and examined. This examination allows for a more precise prediction of the disease course. If lymph nodes have already been invaded by tumour cells, the surrounding lymph nodes should be removed completely.
In Germany, it is recommended to initiate immunotherapy in addition to surgery if the melanoma has penetrated further than 2 mm. The active substance stimulates the body’s immune system. Any remaining, non-visible tumour cells are thus attacked.
Treatment in case of metastasis
If metastasis is already present in the inner organs (e.g. lungs, bones, liver, brain), radiation therapy, chemotherapy, immunotherapy, combined chemo-immunotherapy and targeted therapy can be used in addition to surgery.
For chemotherapy, several different substances are available. Remission of metastasis can thus be achieved and help provide relief from tumour-related symptoms.
Clinical classification in daily practice before histological data is available foresees three stages, whereas Stage I is the exclusive presence of a primary tumour, Stage II includes regional lymph-node metastasis, and Stage III is characterised by the spread of tumour cells by the blood with distant metastasis and organ metastasis in particular.
Staging according to the TNM system
The International Union against Cancer (UICC) published an updated version of the T (Tumour) N (Node; lymph node) M (Metastasis) classification of 1987 which differentiates between Stages I-IV (table 3).
pTis (is = in situ) is used as an abbreviation when there is no presence of a tumour invading deeper but melanocyte growth with mutated cells has already started in the epidermis, and the condition is referred to as melanoma in situ. Using a different classification, this is known as Clark’s Level I. pT0 is used when there is no evidence of the primary tumour.
The different categories of the TNM classification describe the primary tumour (pT) and its local spread.
Invasion of lymph nodes
|Every pT||N1, N2||M0|
|Stage IV||every pT||every N|
1. Primary tumour (pT)
pT1 Tumour 0.75 mm or less in thickness and invades the papillary dermis (Clark’s Level [spread of tumour] II)
pT2 Tumour more than 0.75 mm but not more than 1.5 mm in thickness and/or invades to the papillary-reticular dermal interface (Clark's Level III)
pT3a Tumour more than 1.5 mm but not more than 3.0 mm in thickness
b Tumour more than 3.0 mm but not more than 4.0 mm in thickness
Tumour invades the reticular dermis (Clark's Level IV)
pT4a Tumour more than 4.0 mm in thickness and/or invades the subcutaneous tissue (Clark's Level V)
b Tumour more than 4.0 mm in thickness and/or satellite(s) within 2 cm of the primary tumor
In case of discrepancies between tumour thickness and level, the pT category will be chosen according to the respective least favourable finding.
2. Lymph nodes (N)
N0 no regional lymph nodes metastasis
N1 metastasis 3 cm or less in greatest dimension in any regional lymph node(s)N2 metastasis more than 3 cm in greatest dimension in any regional lymph node(s) and/or in-transit metastasis between primary tumour and first lymph node location more than 3 cm
3. Distant metastasis (M) (in inner organs, brain, bones, soft tissue)
M0 no distant metastasis
M1 Distant metastasis
When classifying with the pT categories it is assumed that the critical tumour levels (0.75; 1.5; 3 and 4 mm) mark biological regions with different prognoses or survival rates. Large-scale statistical investigations have shown, however that the relationship between survival rate and tumour thickness is linear-proportional without “leaps” so that the TNM classification given above should be revised in the future. Until a generally accepted updated version becomes available, the version as outlined here remains valid.