The goal of this study is to develop an effective, sensitive blood test that can detect early tumours in patients with known or suspected hereditary cancer syndromes (HCS). If this new blood test is accurate, it could be used to screen patients for cancer and allow for earlier cancer detection. The study will also use questionnaires and interviews to understand how patients feel about incorporating these tests into routine medical care, and the perceptions of the medical value of test results.

The objective of this protocol is to develop a method to detect early signs of cancer in 'previvors' (people with HCS that do not yet have a cancer diagnosis). This will enable prediction of cancer onset so that patients and their doctors can make decisions to treat or prevent the cancers. HCS patients will be recruited from across Canada to provide blood samples before and after cancer diagnosis. In parallel, there will be development of a circulating tumour DNA (ctDNA) -based test to detect early stage cancer and evaluation on the cost-effectiveness and feasibility of integrating such screening protocols into routine clinical care. In concert, consultation with patients and health care providers will occur to create recommendations for use within clinical care.

CHARM1 leads into its follow-up study, CHARM2.

Inclusion Criteria:

1. Individual with any known or suspected hereditary cancer predisposition (i.e. individuals with an identified pathogenic or likely pathogenic variant in a cancer predisposition gene and/or a family history of cancer without an identified gene mutation) at any stage in their cancer journey (ie: cancer survivor, unaffected with cancer, current cancer patient).
2. Individual must be greater than 18 years of age
3. Individual must speak English or French to participate in the qualitative interview and/or survey

Exclusion Criteria:

1. Individuals that do not meet the outlined inclusion criteria.

The population to be studied includes:

1. Any individual that underwent clinical genetic testing for hereditary breast and ovarian cancer syndrome or Lynch Syndrome and was found to carry a detectable variant that is likely pathogenic or pathogenic.
2. Any individual with a suspected cancer predisposition that has not yet received genetic testing.
3. Any individual who received negative genetic test results but has a strong personal or family history of cancer.