Skip to content
Back to news

Rare cancers and rare diseases: A common approach to treatment

Nearly 20 million: this alarming figure is the number of people newly diagnosed with cancer each year worldwide1. Of these, six out of every 100,000 cancer cases in Europe is a rare form2. For these patients, it is often tantamount to a difficult treatment journey. On top of learning of their diagnosis, the rarity of the cancer type means that existing health options are inappropriate, few in number, or even non-existent. This leads to an everyday life that often resembles that of patients with rare diseases.

A) Rare cancers: A rare disease by definition

A type of cancer is considered rare when its incidence is less than six in 100,000 people per year in Europe, and less than 15 in 100,000 people per year in the United States2. Today, several hundred rare cancers exist (esophageal cancer, certain ovarian tumors, nasal cavity tumors, etc.), accounting for nearly a quarter of all cancers, or one out of every four cancers3.

The incidence of a disease refers to the number of new cases recorded in one year in a population4.

Beyond the statistical criterion, the rarity of the cancer may also result from and unusual location of the tumor (cornea, tongue, etc.) or from their complexity – for example, linked to a specific mutation. Alternatively, rarity may stem from the patient’s situation (pregnancy, organ transplant recipient, or with an infection such as HIV, etc.). These types of cancers often combine several characteristics.

This is the case, for example, in brain cancers, which are relatively rare and hard to treat. In adults, diffuse glioma is the most common type of malignant brain tumor. Unlike brain tumors considered secondary, which are metastases developing from a cancer located in another organ, gliomas develop from glial cells that surround neurons and support their function.

Metastatic cancer is cancer that has spread from the place where it first appeared to another part of the body.

Beyond the unusual location of the tumor, its incidence is less than five out of 100,000 in the United States5

Did you know?

Glial cells are found in the neurons’ environment. They account for almost 50% of brain volume, and play a vital role in maintaining homeostasis and protecting nerve tissue by supplying nutrients and oxygen, eliminating dead cells, and fighting pathogens.

Issues shared with rare diseases

Today, one of the struggles for networks of patients with a rare disease is, in fact, to break away from the label “rare.” Because while individually they are rare diseases, cumulatively, they affect hundreds of millions of people6.

The rare disease (including rare cancer) patient network is one that is particularly active and organized, mobilized around three main issues:

  • Improving diagnosis, so that treatment can begin earlier, in order to overcome the lack of screening available for these diseases
  • Boosting R&D to promote innovation and the development of therapeutic treatments
  • Improving access to treatment, accounting for geographical specificities


More than 9,000 rare diseases have been identified to date7

25 million

people are affected by a rare disease, including rare cancers, in Europe8

Did you know?

All pediatric and adolescent cancers are considered rare.

The “snowball” effect of rarity

Rare diseases, including rare forms of cancer, are difficult to diagnose because of their rarity. This is due in part to the lack of medical history and the lack of knowledge on the pathology. When few patients are affected by a disease, there will automatically be fewer experts in this field. Ultimately, this means fewer therapeutic treatments and innovations. While the incidence of rare diseases becomes quite commonplace when considered cumulatively, the basic scientific research, clinical studies and approval of new therapies in this area are still limited.

The diagnostic odyssey

The fairly lengthy period during which a patient has not benefited from a definitive diagnosis for their disease is called the “diagnostic odyssey.” On average, it is estimated that only half of all rare disease patients have obtained an accurate diagnosis. For more than 25% of patients9, an accurate diagnosis generally takes around 5 years, a length of time that is the direct consequence of the lack of knowledge on rare cancers and the forms they take.

Beyond the patient’s incomprehension and suffering, the diagnostic odyssey also has significant consequences on health care systems: the multitude of consultations, administration of inappropriate medication, etc. These are substantial socio-economic impacts that often remain overlooked.

Unfavorable diagnoses

Late diagnosis also means late management and an often more pessimistic one due to progression of the cancer since appearance of the first symptoms. Today, rare cancers are considered to be responsible for 25% of cancer deaths10. Oftentimes, the prognosis is worse than for patients with a less rare form of cancer.

The geographical challenge

One of the major difficulties is the geographical distribution of patients, who live in very different regions and countries. For example, this complicates recruitment for clinical studies. Should we bring patients together in one place? Should we monitor them remotely? How do we take into account the unique characteristics of each patient? There are so many questions that challenge the relevance of a traditional clinical study.

More appropriate clinical studies

Development programs often need to be tailored to the cohort. To define the size, statistical data for the disease in question is now the basis, rather than standards that are unsuitable for this type of disease. For micro-rare and nano-rare diseases, which have an incidence of less than 30 people11, some clinical studies may sometimes involve only one patient.

By reproducing mechanical, chemical and organic processes as they occur in the patient’s body, including at the cellular level, digital twins can offer a second way to meet this challenge. They accurately simulate the behavior of a drug by providing a complete picture of the disease. To this end, Servier signed a partnership in pancreatic cancer and Parkinson’s disease with Aitia, the leader in the development of digital twins.

Developing the diagnostics

As new rare diseases are discovered and clinical cases are combined, the medical history of each of these diseases can be built. This information is essential for identifying common biomarkers and segmenting patient profiles.

Training experts

In order to improve patient care, governments have encouraged training an increasing number experts in recent years. This is the case for France, which in 2009, developed the “expert center” label granted to institutions that accommodate patients with rare cancers, via the French National Cancer Institute. The Foundation for Rare Diseases addresses the needs of patients with a rare disease with tumor development, but not the rare cancers identified. In such expert centers, the aim is to:

  • Create centers of expertise with specific kinds of health care professionals in order to pool their specialties
  • Bring patients together to foster information-sharing and a better understanding of disease symptoms and evolution
  • Provide answers to questions from patients and their loved ones
  • Accelerate the availability of treatments to patients and possibly allow them to be included in clinical trials

As an independent health care player committed to therapeutic progress, we are able to direct our innovation efforts toward specific patient needs. Our goal is to bring real therapeutic innovations to patients with substantial unmet needs.

[1] Worldwide cancer data | World Cancer Research Fund International (
[2] Cancers rares de l’adulte [Rare Adult Cancers], French National Cancer Institute, (viewed in April 2024)
[3]  (viewed in April 2024)
[4] (viewed in April 2024)
[5] Quinn T Ostrom, Mackenzie Price, Corey Neff, Gino Cioffi, Kristin Waite, Carol Kruchko, Jill S Barnholtz-Sloan, CBTRUS Statistical Report: Primary Brain and Other Central Nervous System Tumors Diagnosed in the United States in 2015–2019, Neuro-Oncology, Volume 24, Issue Supplement_5, October 2022, Page 52
[6] (viewed in March 2024)
[8],un%20an%20et%205%20ans.  [Not available in English] (viewed in April 2024)
[9] [not available in English] (viewed in March 2024)
[10] Rare Disease Day 2022: IARC highlights the burden of rare cancers – IARC ( (viewed in April 2024)
[11] Crooke S. Progress in molecular biology and translational science addressing the needs of nano-rare patients – ScienceDirect
[12] [not available in English]