Genetic Medicine and Services

General Information about Hereditary Cancer and Genetic Counseling in Japan

Understanding Genetic Testing for Cancer: What You Need to Know

Cancer is common. About 1 in 2 people will develop it in their lifetime. While environmental and lifestyle factors like smoking, diet and certain infections may influence your risk, around 1 in 10-20 people with cancer were born with a genetic change that increased their risk.
This is known as hereditary cancer.
Genes carry the instructions your body needs to develop, grow, and stay healthy—like pages in a manual. They protect you from cancer, but mutations or changes in genes can cause cells to grow abnormally, which can lead to cancer. These changes can run in families and may be passed on from parents to children.
Genetic testing looks for mutations in genes that increase the risk for cancer. If one is found, doctors may recommend extra screenings or preventive steps. Testing can show if you are at higher risk than the general population, but it does not guarantee you will get cancer, and you can still develop cancer even if no mutation is found.
It can help you and your family make informed health choices. Some people choose testing to take control of their health, so they can get screened more often if they are at higher risk.
Others may choose not to have testing because it can cause stress or worry. Testing is always optional.

How Genetic Testing Helps Assess Your Cancer Risk

Genetic testing can help you understand your risk for cancer, even if you have not had cancer. It may be especially helpful if:

• You have a family history of cancer
• Several relatives had the same type of cancer
• Either you or one of your relatives was diagnosed younger than 50 years old
• Either you or one of your relatives had rare cancer*
• Either you or one of your relatives had multiple cancers.

These patterns may suggest an inherited genetic mutation. In fact, about 5–10% of cancer patients have an inherited genetic mutation related to cancer. Testing can clarify your risk and help guide health decisions.

* Rare cancer refers to any type of cancer diagnosed in a small number of people each year, such as sarcomas, neuroendocrine tumors, or paraganliomas.

The Role of Genetic Counseling: Guiding You Through Testing & Results

Genetic specialists, including clinical geneticists, genetic nurses and genetic counselors, are trained professionals who help you understand your cancer risk and guide you through genetic testing. When you meet with one of them, they can help you in several ways, including:

• Reviewing your family history to assess inherited cancer risk
• Explaining testing options, results, and whether testing is right for you
• Offering support for emotional and practical concerns
• Help plan regular cancer screenings based on your risk

The types of genetic tests for hereditary cancer available to patients in Japan can vary by clinic, as many genetic tests are not yet reimbursed by The National Health Insurance system but offered as patient-funded tests, which are selected by each hospital. These include single-site for known family mutations, single-gene testing or multi-gene panels that are tailored to your specific needs, and comprehensive tests that look at many known cancer-related genes. In Japan, some genetic testing such as tests for hereditary breast and ovarian cancer syndrome, is covered by National Health Insurance if certain criteria are met. Your genetic specialists will help choose the option that makes the most sense for you.

If you choose genetic testing, results can be:

• Positive: A mutation is found that raises your cancer risk. This does not mean you have cancer, but it can guide prevention and screening.
• Negative: No mutation is found, so there is no current genetic evidence for your personal or family history of cancer.
• Variant of uncertain significance (VUS): A genetic change is found, but we do not yet know if it increases cancer risk.

If your test comes back positive for a genetic mutation linked to a higher cancer risk, genetic specialists will guide you on next steps. People with higher genetic risk can choose more frequent screening. For example, if there is an increased risk for breast cancer, then a person will get screening tests such as mammograms more frequently and from an early age. If someone is at risk of colon cancer, then they may choose to have colonoscopies earlier in life. The goal is to prevent cancer or catch it early when it is easier to treat.

How to Prepare for Genetic Testing: Steps & What to Expect

Specialized services like clinical genetics often require a referral from a primary care provider in Japan. It is possible to make an appointment without a referral at some hospitals; however, please note that there may be an additional consultation fee that may apply without a referral. In some cases, a referral from a medical provider outside Japan may be accepted, but it is important to check directly with the hospital to confirm what is needed before your visit.

In Japan, National Health Insurance usually covers genetic testing only for individuals diagnosed with certain types of cancer or who are suspected of having hereditary tumors, such as retinoblastoma, multiple endocrine neoplasia types 1 and 2, neurofibromatosis types 1 and 2, tuberous sclerosis complex and hereditary breast and ovarian cancer (as of 2024). Even for people with hereditary cancer syndromes, testing and surveillance are often paid out of pocket if they do not have a cancer diagnosis. Genetic specialists can help you understand the costs and explore your options.

It is important to think about how genetic testing might affect other areas of your life. In Japan, there are no clear rules to protect against genetic discrimination, so your test results could affect things like getting private insurance. Recent movements in Japan include the enforcement of the Law for the Promotion of Genome Medicine（Linked at external site）, a series of statements issued by the Life Insurance Association of Japan（Linked at external site） and the General Insurance Association of Japan（Linked at external site）, and the inclusion on prejudice and discrimination related to genomic (genetic) information in the “Fiscal 2025 Emphasis of Awareness-Raising Activities.”（Linked at external site） If you live outside Japan or plan to move, be sure to check the laws in that country, as protections can be different.

Familial Genetic Testing: When Hereditary Cancer Runs in the Family

Familial variant testing, also called targeted, single-site, or cascade testing, checks for a known genetic mutation in a family. Instead of testing an entire group or panel of genes, this test focuses only on the known mutation.
This type of testing provides two possible results:

• Positive: You inherited the same genetic mutation linked to an increased risk of cancer.
• True Negative: You did not inherit the mutation, meaning your cancer risk is the same as the general population.

If you or a relative has been diagnosed with cancer and/or a genetic mutation has been identified, it is important to share this information with relatives so they can consider genetic testing.

Genetic Counseling at the National Cancer Center Hospital (NCCH)

Department of Genetic Medicine and Services

We opened our Genetic Counseling Outpatient Clinic in 1998, making us one of the first such clinics in Japan's cancer care field. We initially focused on genetic testing for hereditary colorectal cancers and retinoblastoma. Over the years, we have continued to adopt the latest genetic and genomic analysis technologies and expertise, partly thanks to working closely with the NCC Research Institute located on the same campus.

Our clinics provide genetic counseling and testing for patients who may have hereditary cancers and their family members. We welcome a wide range of patients and their relatives, including people with rare cancers or simply those with general concerns and questions about cancer and heredity.

Our Mission

Our mission at NCCH is to provide personalized support and accurate, up-to-date information about genetics, hereditary cancer, and genetic testing in a respectful, compassionate environment.
What we offer:

• Genetic counseling and genetic testing for individuals who may have a hereditary cancer risk.
• Research-based genomic analysis employing advanced genetic technologies to investigate cancer risk.
• Research on cancer screening and surveillance methods for patients with hereditary cancer.
• Collaboration with international genetic specialists in research and clinical practice.

Examples of Hereditary Cancer Consulted

Hereditary breast and ovarian cancer syndrome (HBOC), Lynch syndrome, Familial adenomatous polyposis (FAP), Retinoblastoma (RB), Li-Fraumeni syndrome, Multiple endocrine neoplasia type 1 (MEN1), Multiple endocrine neoplasia Type 2 (MEN2), Neurofibromatosis type 1 (NF1), Neurofibromatosis type 2 (NF2), Peutz-Jeghers syndrome, Juvenile polyposis syndrome, Cowden syndrome, von Hippel-Lindau disease, Hereditary paraganglioma-pheochromocytoma syndrome, Hereditary pancreatitis, Hereditary papillary renal cancer, Tuberous Sclerosis Complex, etc.

Note：We also offer genetic counseling and genetic testing for hereditary cancer not listed here. Please do not hesitate to contact us for more information.

How to Make an Appointment

New patient appointment dates

Monday, Tuesday, and Thursday afternoon

How to make a reservation

For Japanese-speakers: To make a reservation, please call our reservation center: [+81-3-3547-5130 (weekdays, 9 AM to 4 PM)]. Visit our appointment page for details [【初診】電話予約]. After booking, we may contact you by phone to collect details about your concerns and requests. This call is for preparatory purposes only and is not considered a counseling session. A referral from your primary care provider in Japan or from your international genetic specialists (genetic counselors) is required.

For non-Japanese speakers: Please visit our appointment page [International patients]. A referral from your primary care provider in Japan or from your international genetic specialists (genetic counselor or primary care provider) is required.

Note: Telephone consultations are not available. While we are able to offer basic genetic counseling in English, we kindly request that international patients with limited Japanese proficiency make arrangements to use an interpreter or translation service. Please follow the link below for information specific to international patients when requesting an appointment: https://www.ncc.go.jp/en/about/appointments/index.html

Genetic Counseling Fee

Our clinic offers genetic counseling through National Health Insurance or self-pay. Genetic testing is a separate service, and costs vary based on the test and insurance coverage. During your session, genetic specialists will assess your needs and recommend testing, but counseling and testing are billed separately.

Communication Tools for English-speakers

Genetic Testing Terms Explained: A Glossary for Patients

Checking the glossary before your appointment can help you learn key terms, how to say them, and their translations. This can make understanding your medical staff easier.

Word	Pronunciation	Translation
臨床遺伝専門医	Rinshō iden senmon-i	Clinical Geneticist
腫瘍内科医	Shuyō-naikai	Oncologist
遺伝子	Idenshi	Gene
ゲノム	Genomu	Genome
遺伝子検査	Idenshi kensa	Genetic Testing
変異	Hen-i	Mutation
家系図	Kakeizu	Pedigree
家族歴	Kazoku-reki	Family History
病歴	Byoureki	Medical History
遺伝性	Iden-sei	Hereditary
医療保険	Iryō hoken	Medical Insurance
がん（癌）	Gan	Cancer
常染色体顕性(優性)遺伝	Jōsenshokutaikensei(yūsei)-iden	Autosomal Dominant Inheritance
常染色体潜性(劣性)遺伝	Jōsenshokutaisensei(ressei)-iden	Autosomal Recessive Inheritance
多因子	Ta inshi	Multifactorial
症候群	Shōkōgun	Syndrome

Letter Template: Explain your situation

If you have a family history of cancer or a known genetic mutation, accessing genetic testing in Japan can feel overwhelming. A letter has been created (available in English and Japanese) for patients to download and share with Japanese healthcare providers.
The letter explains:

• The type of genetic testing you are seeking
• The reason you are seeking genetic services
• A brief explanation of your personal or family history related to cancer and insurance coverage

Click the link to download the letter: [Genetic Counseling Support Letter（Word：1.87MB）]