The number of new cancer diagnoses has been rising steadily for years. According to estimates by the World Health Organization’s International Agency for Research on Cancer (IARC), the cancer incidence in people aged from 0 to 90 years worldwide was 19.3 million in 2020.1 This incidence is predicted to increase by another 10 million up to around 30.2 million new cancer diagnoses worldwide in the next 20 years.2 Cancer is also still one of the most common causes of death worldwide. In 2020 alone, an estimated 9.9 million people worldwide died from cancer.3
The growing incidence of cancer is mainly due to our ageing society, as age is an independent risk factor for the development of cancer. At the same time, the possibilities for the early detection of cancer are developing, e.g. through growing implementation and comprehensive use of preventive cancer screening programmes worldwide.
Another component in future early detection of cancer is the increase in development of new molecular methods (e.g. “liquid biopsies”), designed to detect circulating cancer cells in human body fluids. Multicancer detection tests are being tested in population trials to check their potential as future new cancer screening methods. It is likely that new molecular methods for detection of early cancer will also have an impact on the figures of cancer incidence in the future.
The predicted increasing cancer incidence and the still very poor prognosis of certain types of cancer, e.g. malignant brain, pancreatic or blood cancers, are posing a challenge to researchers in cancer medicine who are pursuing the goal of developing ever more effective therapies.
For decades, cancer medicine focused on the direct removal of malignant tumours or the destruction of cancer cells. The most important pillars of cancer therapy are the oncological surgical resection of tumours, chemotherapy and radiological radiation. Surgical procedures and treatment protocols have been continuously developed and they remain effective cornerstones of cancer treatment to this day.
The usual goal of classical cancer therapy is the complete removal of a malignant tumour. When the tumour is resected, a margin around the tumour is maintained and, as a rule, the associated lymphatic drainage area of the resected organ or organ part is also removed (oncological resection). Tumour resection and lymph node removal serve to minimise the risk of tumour recurrence and thus improve the survival prognosis. Chemotherapy and radiotherapy after (adjuvant) or before (neoadjuvant) surgery also serve to reduce the risk of a recurrence by destroying potentially remaining cancer cells.
The Arrival of Immunotherapy
In recent years, various new therapeutic measures have been added to the tried and tested forms of therapy. A new era in cancer research and treatment began early in the 21st century: the era of immunotherapy. Immunotherapies are, in the broadest sense, substances that support the immune system in its response to various external threats, such as cancer cells.
Initially, researchers studied cancer cells and their specific characteristic features. An important step in this context was the introduction of so-called “biomarker testing”. Biomarkers are biological characteristics that can be measured and assessed in blood or tissue samples – including cancer cells.
Changes in the expression or quantity of certain genes can now be determined molecularly and provide information about the specific characteristics of a cancer. Cancer cells sometimes show very typical characteristics on their surface, called “tumour-specific” or “tumour-associated” antigens. These are found either not at all or only in a different form or frequency on healthy body cells.
Based on these cancer-typical characteristics, targeted therapies can be developed to eliminate cancer cells more effectively. The research focus lies primarily on specific characteristics favouring cancer cell proliferation and spread in the human body. By targeting these characteristics with specifically tailored drugs, many types of cancer can be inhibited in their growth more effectively.
Testing cancer tissue for specific biomarkers also has the advantage of sparing patients from ineffective or less effective therapies in the absence of these biomarkers.
In 1997 and 1998 respectively, the first targeted immunotherapies in the form of monoclonal antibody therapies were approved: rituximab for patients with previously treatment-resistant B-cell non-Hodgkin’s lymphoma, and trastuzumab for the treatment of HER2-positive breast cancer.4
Cancer research today is not focusing only on the field on specific features of cancer cells, but also on how the human immune system with its different cell types and messenger substances acts against cancer cells. Intensive research of the detailed processes of the human immune system’s response to cancer is contributing to the development of further immunotherapies.
The aim of these types of immunotherapies is essentially to support and strengthen the human immune system in its fight against cancer cells. Various immunological approaches are now available.
Overview of Immunotherapies