The many different types of rare oncological diseases include tumors of the body and hematological disorders of the blood. Although individually these malignancies are rare, as a group, they represent a significant majority of people with cancer.
Certain characteristics of these malignancies differentiate them from more common types of cancer. Often, the cancer begins in a type of cell that only rarely becomes cancerous. This can happen in organs that are otherwise common sites of cancer growth. For example, although breast cancer is not a rare disease, angiosarcoma of the breast, which arises in the inner lining of blood vessels, is a rare cancer.
Rare cancers can originate in almost any organ of the body. Examples include gastrinomas (from gastrin-producing small intestine cells), childhood acute myeloid leukemia (from myeloid blood cells), schwannomas (from the sheath cells covering nerves), retinoblastomas (from retinal cells), or thymomas (from thymus gland cells).
For some of these cancers, specialized treatments have not yet been developed. On the whole, however, research in rare cancers is extremely active, with many drugs either approved or in development.
Medical history and physical exam are the first steps in a rare disease being properly diagnosed. Symptoms of malignancies vary significantly in different disease types. Some malignancies tend to cause few symptoms, meaning patients often seek no care until the disease is relatively advanced. Slow-growing cancers also can be less likely to be detected early on, while certain rare malignancies cause relatively unusual symptoms that a primary care practitioner might be less likely to notice.
Physical exams reveal clues, and lab tests divulge more. Basic blood work can uncover hematological malignancies. Pathologists may be able to diagnose cancer after viewing the cells under a microscope, although for rare cancers, multiple tests on the tissue sample may be necessary, prolonging the process. For the most part, once a malignancy is recognized, oncologists and pathologists working together make a specific diagnosis in a reasonably short time.
Treatment for rare cancers is usually a team effort, with general practitioners, oncologists, hematologists, radiation specialists, surgeons, and other physicians consulting with one another. Treatment —usually a combination of treatments—is tailored to the type of malignancy and its stage. Surgery may remove or debulk the cancer; chemotherapy or radiation therapy can kill cancer cells. For some patients and conditions, targeted therapies (a subset of chemotherapy) can be used to kill cancer cells more specifically than standard chemotherapy. Additional treatments may include immunotherapy, to help the immune system fight off cancer cells, or hormone therapy, to slow the growth of cancers responsive to hormones.
In most cases, cancer specialists shape the treatment plan based on clinical guidelines, patient preferences, and treatment response. For certain rare cancers, an established treatment plan may not exist, so medical professionals may use a treatment plan adapted from those for other types of cancer.
Research in rare oncology diseases is very active. Some trials are developing and testing new drugs, while others are focusing on comparing the effectiveness of known drugs in specific situations.
Some study the initial use of therapy and others study therapies following a nonresponse to treatment or disease recurrence. A small sample of clinical trials currently planned include:
Leflunomide with Procarbazine: glioblastoma multiforme
Regorafenib: neuroendocrine tumors
Everolimus: refractory testicular germ cell cancer
Proton beam therapy versus conventional radiation therapy: neuroblastoma
Lanreotide: metastatic Merkel cell carcinoma
Carboplatin ocular injection: retinoblastoma
Advocacy Support and Information
Advocacy groups provide an important resource for patients, caregivers, and clinicians, offering introductory educational materials and practical advice for dealing with these conditions, as well as more detailed information about recent research papers, current clinical trials, etc.
They also provide an avenue for social support and for learning from other families who have experience dealing with these diseases.
Below are some advocacy groups focusing on rare cancers: