This study looks at how **cannabis** (a plant) and **cannabinoid** (a compound from cannabis) use affects people with certain **cancer** types. It follows 2000 adults newly diagnosed with **breast, colorectal, melanoma, non-Hodgkin lymphoma**, or **non-small cell lung cancer**. These patients are about to start cancer treatments like **chemotherapy** or **immune checkpoint inhibitors (ICIs)**, which help the immune system fight cancer. Participants will answer monthly surveys for a year and have their medical records checked. To join, you must be 18 or older, have a new diagnosis of one of the listed cancers, and plan to start treatment. You need to understand English or Spanish and have an email for surveys. **Key Points:** - Participation involves monthly surveys for one year and medical record checks. - Must be willing to complete surveys online and have a diagnosis of specific cancers. - Not suitable for those already in supportive treatment trials or with certain health conditions.

Note: Only some sites offer an optional sub-study with additional requirements, including specific treatments.