In such a delicate issue as tan topless - "FOR" is justified only cosmetic and visual effects, all steel moments "AGAINST" to sunbathe topless (topless- without top), because even a completely healthy person in this case automatically classify themselves in risk of breast cancer and other organs.
As the activities of all organs and systems of the human body are interrelated, it is enough to happen dysfunction in one organ and it can lead to irreversible processes in the other, and ultraviolet irradiation in this case is a provocative and quite a significant factor.
Sun exposure could negatively affect the endocrine glands (thyroid, ovaries, and so on.) Changing hormonal imbalances and promoting female sex hormones (estrogen and progesterone). This in turn leads to changes in the breast tissue to form knots therein, seals, tumors are exposed to the sun can regenerate from benign to malignant tumors.
And the moment of formation may go unnoticed, and the process of reversible changes (when possible to recover organ tissue), so will be missed. Because of its structure, the breast tissue is more susceptible to UV, moreover exposed portions of the body itself will perceive tan than flat surfaces, respectively, the strength is increased sun exposure.
Before sunbathing topless, even in the absence of any wrongdoing on the part of health, it is worth considering the possible consequences, and look at the statistics of breast cancer that is growing inexorably. Perhaps this is not a beauty, you must pay for health. Only a healthy body is beautiful!