In the last decade, an overwhelming number of genetic aberrations have been discovered and linked to the development of treatment for cancer. With the rapid advancement of next-generation sequencing (NGS) techniques, it is expected that large-scale DNA analyses will increasingly be used to select patients for treatment with specific anticancer agents. Personalizing cancer treatment has many advantages, but sequencing germline DNA as reference material for interpreting cancer genetics may have consequences that extend beyond providing cancer care for an individual patient. In sequencing germline DNA, mutations may be encountered that are associated with increased susceptibility not only to hereditary cancer syndromes but also to other diseases; in those cases, disclosing germline data could be clinically relevant and even lifesaving. In the context of personal autonomy, it is necessary to develop an ethical and legal framework for how to deal with identified hereditary disease susceptibilities and how to return the data to patients and their families. Because clear legislation is lacking, we need to establish guidelines on disclosure of genetic information and, in the process, we need to balance privacy issues with the potential advantages and drawbacks of sharing genetic data with patients and their relatives. Importantly, a strong partnership with patients is critical for understanding how to maximize the translation of genetic information for the benefit of patients with cancer. This review discusses the ethical, legal, and counseling issues surrounding disclosure of genetic information generated by NGS to patients with cancer and their relatives. We also provide a framework for returning these genetic results by proposing a design for a qualified disclosure policy.