Mars gets debilitated when it is placed in the sign of Cancer, which means that Mars becomes very weak by virtue of its placement in this sign. Retrograde debilitated Mars in the fourth house of a horoscope becomes one of the most significant planets in that horoscope due to which it should be studied very carefully. This is due to the reason that when retrograde debilitated Mars is placed in the fourth house of a horoscope in the sign of Cancer, the sign Aries ruled by Mars falls in the first house of that horoscope. Hence Aries becomes the first house or ascendant of that horoscope and Mars being the planetary lord of the sign Aries becomes the lord of the first house or the lord of ascendant in such horoscope.
Since the house of ascendant is the most important house of a horoscope, the effect of any benefic or malefic influence on this house of a horoscope can reflect in the entire horoscope, positively or negatively, depending on whether the influences affecting this house are positive or negative. Similarly, any type of weakness or strength experienced by the lord of ascendant in a horoscope can also affect the entire horoscope significantly, positively or negatively. When retrograde debilitated Mars is placed in the fourth house of a horoscope, the lord of ascendant becomes debilitated and hence the entire horoscope becomes weak. There are no doubts that when retrograde Mars is placed in its sign of debilitation in the fourth house of a horoscope, the chances of such horoscope behaving in strong manner are reduced as the lord of ascendant for such horoscope is very weak. Therefore, even benefic retrograde debilitated Mars placed in the fourth house of a horoscope may not do much good for the native as it indicates weakness to the entire horoscope.
However all is not lost and there are still many factors that can strengthen and improve such horoscope, as no single planet can govern an entire horoscope on its own, whether such planet is weak or strong, positive or negative; and even if such planet is the lord of ascendant in a horoscope. The influence of benefic planets on the first house of such a horoscope or the influence of benefic planets on such retrograde debilitated Mars in such a horoscope can provide extra strength to the horoscope and the results may improve. However the influence of malefic planets on the first house of such a horoscope or the influence of malefic planets on such retrograde debilitated Mars in a horoscope can make the situation even worse. This is due to the fact that such malefic influences can further weaken the overall positive energy of such horoscope due to which the native may have to suffer a lot in many spheres of his life. Therefore, when retrograde debilitated Mars is placed in the fourth house of a horoscope, strong positive influences are required to make such horoscope work in a positive manner as otherwise, such horoscope may become negative or very weak.
When joined by other benefic planets, retrograde debilitated Mars in the fourth house of a horoscope can bless the native with good results related to marriage, profession, fame, authority and many other types of good results depending on the overall tone of his horoscope. Such benefic retrograde debilitated Mars can bless some natives with success through professions related to the domain of science due to which these natives may become doctors, engineers, scientists and other such professionals. Some other natives under the influence of benefic retrograde debilitated Mars in the fourth house may engage in the field of education and they may shine as teachers, book sellers, owners of educational institutes and other such professionals. Benefic retrograde debilitated Mars in the fourth house can bless some natives with creative abilities and hence these natives may become successful as designers, actors, poets, architects, musicians and other such professionals. Apart from this, benefic retrograde debilitated Mars in the fourth house can bless the natives with good results through many other fields of professions as well as through many other spheres of their lives, depending on their overall horoscopes.
On the other hand, malefic retrograde debilitated Mars in the fourth house of a horoscope can trouble the native with problems related to marriage, profession, health and many other types of problems depending on the overall tone of his horoscope. Some natives may feel the heat of his malefic retrograde debilitated Mars in the field of their health due to which they may suffer from various types of health issues and diseases which may become serious if this malefic retrograde debilitated planet attracts support from other malefic influences in one such horoscope. In extreme cases when supported by other malefic planets, malefic retrograde debilitated Mars in the fourth house of a horoscope can afflict the native with a serious and permanent type of disease which may trouble him for many years and which may also reduce his lifespan.