I agree. You can say stress causes the release of stress hormones such as epinephrine or norepinephrine which increase your heart rate, blood pressure, and blood sugar levels. The rise in these may speed up the tumour growth and more likely to metastasize. Furthermore, a person under stress may develop certain behaviours such as drinking alcohol, smoking, overeating leading to obesity. These behaviours contribute towards the increase of your HR, BP as well.