How to edit any kind of selected items in datagridview?

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C#

database

DataGridView

editing

I have created a form where can list all diseases in DataGridView. I can add or delete any kind of diseases. But I still can't edit any diseases which already added into the database.

Here is my code:

if (Form_Diseases_dataGridView.SelectedRows.Count > 0 && MessageBox.Show("Are you sure to edit this disease?", "Edit", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
            {
                Disease disease = (Disease)Form_Diseases_dataGridView.SelectedRows[0].Cells[0].Value;
                Form_Diseases_Add ownDiseaseEdit = new Form_Diseases_Add(disease);
                if (ownDiseaseEdit.ShowDialog() == DialogResult.OK)
                {
                    try
                    {
                        ConnectToDB.EditDisease(ownDiseaseEdit.Disease);
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                        DialogResult = DialogResult.None;
                    }
                }
            }

I have the following error message: System.InvalidCastException: The object cannot be converted from "System.Int32" type to "MyProject.Disease" type.

What I'm doing wrong?

What I have tried:

if (Form_Diseases_listBox.SelectedIndex != -1 && MessageBox.Show("Are you sure to edit this disease?", "Edit", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
            {
                Disease disease = (Disease)Form_Diseases_listBox.SelectedItem;
                Form_Diseases_Add ownDiseaseEdit = new Form_Diseases_Add(disease);
                if (ownDiseaseEdit.ShowDialog() == DialogResult.OK)
                {
                    try
                    {
                        ConnectToDB.EditDisease(ownDiseaseEdit.Disease);
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                        DialogResult = DialogResult.None;
                    }
                }
            }

Well working with ListBox, but I can't find the way have to do it in DataGridView?